Im a bit behind on this thread but I'll drop my $2 (I have no cents!).

I have built a lot of Shuttle pc's and they are great. I have 25 that I
built 2 years ago for a business client running XP Pro and they have yet
to call me for any problems hardware related - only installing new
software.

I have installed Ubuntu on 5 of those for the same client and its run
solidly.

Vista is making me rich! All the people who try it and hate it and are
stuck with a useless pc - I install XP Pro if they ask or I suggest Ubuntu.

The only problem I have found with Ubuntu - or any linux OS is - you
still have to use the command line at some point and that is just simply
beyond some people. But what I tell them is,

lets keep this as simple as possible. What do you want to do?
I want to type a letter.
Ok. Click this link called Writer and you write what you want.
Do you want to calculate something out?
Yes.
This button Calc is a spread sheet.

I just keep it simple and people pretty much use it just like that.

Linux in general scares people because its so different but, if you take
out all the crap and boil it down to "WHAT do YOU WANT to DO", then you
get to use the computer as a tool.

So, to the original poster of this thread, what do you want to do? From
there you will make your choices.