I agree with what Doc John has said about having the 2GB if purchasing Windows Vista.
I have two Compaq desktops that I've had for 5 years each...wonderful great machines. They run XP and I've never had a single issue with either of them...even after daughter downloaded some viruses back in the day from getting MP3's.
I purchased a Compaq notebook and LOVE it!!! It runs Vista, but when I bought it I had many questions...having never owned a notebook, but I had questions about Vista too. I really didn't want it but they had none with XP.
He said I would be alright if I didn't do alot of downloading, gaming and the such...if I did alot of pictures to download them to an external hard drive. He explained that Vista requires MEGA space so I couldn't do alot of those things on my laptop because I didn't put out the extra bucks for the larger RAM.
That's all I know.
I wish you luck!
KD