Please consider using one partition for a separate home partition. This
makes it easy to install and re-install without disturbing your data and
settings. You will be much better served and will be glad you did. I can
step you through it. It isn't hard. However, you may need to either
re-install or move your home to another partition which is not as easy.

If you are using grub and not grub2 then it is just a text file that can be
edited and you can change or alter it to anything that you want. You can set
the default OS to another one. You can edit grub from any OS that you can
boot. You cna also edit grub temporarily on the fly by pressing e on the
line of grub that you want to change. When done making changes just press b
for boot and enter. If you are using grub2 that is another story.

Different flavours of Ubuntu can be installed to the same partition from
Synaptic and then you just need to change the session. Server can be removed
safely and depending on what is listed in grub you can still boot. Even if
it does work you can boot any live CD and rewrite grub. Everything is still
there you just need to rewrite the bootloader.

it sounds like (by what you've written) that you
wish to actually "triple-boot" where you have
Windows, Linux, and Linux as the OSes.

I've done this, using a 160 Gigabyte hard drive,
a separate boot partition and separate home partition to use with
the following operating systems:
1) Windows XP Media Center
2) Mint 32 bit
3) Mint 64 bit
I know this is an Ubuntu group, but in this case I ran Mint.

Anyway, I started out with only windows on the drive,
then I resized the windows partition, and divided up the rest
of the disk to use Linux partitions.

What wound up happening, is that once I installed Linux #1, it
was fine, it discovered Win Xp and did not do any damage to the MBR,
and I was able to boot into either XP or Linux at boot (using Grub).

Then, (this is where it got dicey) once I installed Linux #2 to the drive,
all broke loose in that only itself and Win XP were detected, ---Linux #1 was
not recognised, and this caused a new creation/installation of Grub so that
Linux #2 or Win XP could boot. It completely ignored Linux #1.

As a temporary workaround, I merely edited the GRUB file of Linux #2 to
make it aware of Linux #1.

Summary. This was a pain in the butt. Any kernel update to Linux #1 would
have to be accounted for manually in Grub of Linux 2.
And, from time to time (Not every boot mind you) the system would
experience Ubuntu Busybox errors where it could not find the particular
boot partition that it would need to find to boot the desired Linux OS.
Windows stayed out of this mess and was generally always able to boot up.

So, my advice is to be really careful how you set up the partitions.
Ideally, you'd want a GRUB file that was aware of both of your Linux OSes,
but a Single Grub file, not 2 of them, on the system. I am not sure of how this
can be done.

I like the idea of using a separate partition for my home partition. You could
please send me the details of how to do it. (I will go for that when next I am
installing a Linux system ... hopefully soon.) But on my current system, I am
using grub (not grub2) so i think it will be easier to just edit the grub file.

Like Adam mentioned, I have 3 OSes (so its a triple-boot). And I think its the
GRUB file of the most recently installed Ubuntu (in my case Ubuntu Server) that
is controlling the boot sequence. It duely recognizes the Win XP & Ubuntu
Desktop but my question is can I make the GRUB that came with the Ubuntu Desktop
to control the boot sequence?

I want to be able to delete the Ubuntu Server (or wipe its partition) anytime I
dont need it again without fear of losing my GRUB. Is that possible? Or will I
have to use the Live CD to re-install GRUB anytime I do that?

"can I make the GRUB that came with the Ubuntu Desktop to control the boot
sequence?"

I'm certain you can. But it may require some magic to get this on the MBR. The
MBR needs to know the location of the GRUB file you wish to be the controller
(for lack of a better word). If there's a way to force a write to the MBR that
isn't destructive, then this sounds like the way to go.

Once the MBR accepts that your Ubu Desktop GRUB file is the one to look at, it
should be smooth sailing from there.
Again, I only have the theory in my head, and not the actual steps to do this.
Google is your friend.

You load grub into a text editor with gksu gedit to load the text editor
with root privileges. (Server may not have this in which case use nano
instead of gedit.) Then you navigate the text editor to /boot/grub in the
root file system of your server edition. Then you open the file called
menu.lst. Scroll down to the line that says default 0. Grub uses ordinals
(starts from zero). This means that if you don't press any keys it will boot
the first OS in the list. You can change that number to anything else in
your list. Just remember that it counts in ordinals.

You can do this in one step with: gksu gedit /boot/grub/menu.lst

You can edit grub from any OS that you can boot into. It does not require
that you work from server. Just remember to work on grub in the last OS that
you installed which is likely server since that is the choice that grub
gives you by default. It is easier to launch a root nautilus to change
partitions then navigate to /boot/grub and right click on menu.lst and
choose open in text editor. To get a root nautilus you use gksu nautilus in
a terminal. Do not close the terminal window until you are finished or it
will close nautilus or gedit.

Instructions are provided here:
https://help.ubuntu.com/community/GrubHowto/ChangeDefaultOS
You can learn more about grub here:
https://help.ubuntu.com/community/GrubHowto

I have installed versions from 8.04 on. The latest version 9.10 uses a beta
version of the grub. I have failed to find the menu.lst file with this version.

I simply use the install program and choose the OS side by side to install
another version. I do have a problem though as I installed Ubuntu 9.10 on the
other half's new netbook and the default OS is now Ubuntu 9.10. The problem is
that she likes her Windoze so is unhappy with the idea that she must choose it
from the bottom of the boot menu. Do you have any idea how to change the boot
order so I can save face with her. Remember that the /boot/grub/ folder has no
menu.lst file.

Remember that the /boot/grub/ folder has no menu.lst file.
>
that's the new grub2

I've been meaning to ask about this. I found a file called grub.cfg,
which appears to be the replacement for menu.lst The comments in the
file say that it shouldn't be edited, but I did after backing-up the
original file. It still seems to work OK.

I've changed the delay time, changed some of the text it displays, and
deleted some unwanted entries, by removing the stuff between { ... }.
I've also checked that the default operating system can be changed, if
required.

Is there a better way to make these changes?

There is s a good primer on grub2 in the ubuntuforums:
http://ubuntuforums.org/showthread.php?t=1195275

If you install a fresh version of Ubuntu starting with 9.10 you will get
grub2. If you do an upgrade it will keep legacy grub (not convert it to
grub2). I had thought that you did an upgrade because you mentioned 8.04.
Sorry for any delay in resolving your problem. It appears that you did quite
well on your own which is the best kind of learning.