XP? or Vista?
Only you can determine that. If it works for you, it works. I have client businesses that are still using Windows 98... because it does the job for them. I have on who is still using Windows 95 for a specific application to run an optical topographer... it would cost $10,000 to replace the machine with one that will work woth a later version of Windows.
I have other clients including businesses that switched to Macs and have never looked back... and refuse to look at Windows based software.
I went to Vista but had problems with some of my older software...so I went back to XP. I was never unhappy with the XP-SP2 version.
Vista is pretty and has some neat tricks; but offered nothing I would use a lot. Heck, I like my Corolla better than my turbo Saab and like being self employed more than the higher-income corporate work.
Guess that I’m just weird.
Geez, I’d think they could at least upgrade to 98Se (same core as 95 but less buggy), or maybe they could run in compatibility mode on a newer OS?