A long time ago, Bill Gates said that the thing that caused the most problems with Win98 & WinXP were devices that had poorly written device drivers. WinXP (and Win98) running in VMWare under linux has never ever crashed for me. I set the memory pretty tight, but, vmware uses some pretty generic microsoft supplied drivers for video, etc. It has always seemed that the more bleeding-edge the hardware, the more problems I have seen.
My nephew's machine runs a pretty generic setup with a very run-of-the-mill ATI video card and works flawlessly. He plays video games all day long with it, surfs the net, etc. I don't think his machine had any problems until we installed some USB device driver -- which we quickly removed.
Other than that, ram is good.
If when you are running things you see the drive light blinking a lot when you switch tabs, you might not have enough ram.