Why not use the Update Manager to upgrade on the 10.04 and leave the XP
alone. Hit the settings button in UM to set it to show the upgrades
available without LTS.

When I did that going from 9.10 it really didnt do very well but Ill give it
another try.

A lot depends on how far you are planning to upgrade - one level isn't
too bad ( though that can go wrong ) but more than one version upgrade
is just asking for trouble IMHO - i.e. 10.04 to 10.10 to 11.04 ( can't
go direct from 10.04 to 11.04 ). Only difference is that 10.04 is a
LTS version and could be upgraded to 12.04LTS in one step when it
arrives. Personally, given the huge changes that 12.04 is going to
have I'd think a clean install is the better way to go anyway.

You can use the Ubuntu install CD to do a manual install and erase the
old Ubuntu partitions / create new ones. Get the chance to set a /home
partition too so future clean upgrades are easier :-)

Upgrades are iffy. You will have to upgrade twice to get the latest version,
10.04 -10.10 - 11.04. The chances of this going off without a hitch are
slim. I would backup your data and do a fresh installation of Ubuntu,
leaving XP alone. Save data there, too, just on case. You can try upgrading,
it is your time and effort. I like starting with a clean slate. If you do
this frequently out may be worth extra time to make a third partition for
home. That way you can reinstall and reuse your home, preserving data and
settings.

I have upgraded without a hitch and clean installed so
it is swings and roundabouts in my view. It depends on the speed of
connection of course but that also hold if you have to download an ISO
and burn you are taking that time up. Buying the CD is OK but unless you
buy off a dealer that takes time.

The problem its not just one upgrade but two. The chances of something going
amiss are good and one iso versus two upgrades are probably a time and
bandwidth saver. I agree that upgrades have their advantages, but not in
this case. I am glad that you have had good luck with them.

I strongly suspect that the success of an upgrade, or multiple
upgrades, is what's been done with the OS in the meantime. If it's
just been used 'as is' and only basic programs installed from the
repositories then the chances are higher than an upgrade will go
cleanly. Once programs outside the basic ones or using external
sources are installed then upgrading is more likely to crash out.

On a similar note - there's been a lot of bad press about Win7 SP1
with some users having trouble installing it, or it breaking Win7 if
it does manage to install. Again - on a clean install of Win7 the SP1
update goes in without a hitch.

That its for sure. Sometimes outside sources will cause an upgrade to fail
outright. That is because the dependencies can get out of whack and the
upgrade will attempt to shut off outside sources and upgrade base packages
before it can upgrade the distribution. I have encountered failure more
often than not.
The party line from Canonical is that upgrades are safe.and work. I notice
that Mint which is based on Ubuntu does not encourage upgrading distros.

People who have had success likely have it because they use plain vanilla
Ubuntu while mine its severely modified. That being said upgrading through
two versions really complicates things and there is much room for error. It
could work but it is a question of how much time and effort one is willing
to spend.

In my experience the Win 7 SP1 is really not necessary anyway because it
only contains a bunch of update that happen individual anyway. That is
why the clean install works while the later one does not because the
user has update set auto.

You can go to MS update and turn off SP1 update in those circumstances.