I never thought there was anything wrong with win 98.
Windows xp is fine, and most software should support it. In fact, a lot of stuff may not support windows 8 because it's so new, even though microsoft says everything will work... cough cough bullsh!t....
I haven't messed with windows 8. I completely switched to a mac about a year ago, and I don't regret it. Unfortunately most software in this business will only function on a pc. I've been using vmware fusion with less issues than actually running a pc.