What Hard-Drive setup do you happen to have?
Multi-gig drives are dirt cheap these days and you can actually put ata100 drive at 7200 rpm
for a resonable price.
Dual-Boot might work well for you and then you can decide?
If you have 2 drives with the room on em, Ghost your Win2k drive over to the second and then update the first. This way you have the ability to run your apps under both to really get a feel for each and you do not loose anything or have a pain in the ass if you decide XP is a hosebag.
Personally, if cost is restrictive, XP is not worth the money for the upgrade.
Win 2k is much faster, and as with any windows OS release and the claims of great gains in speed, functionality, ect. Everything you read from MS or hear on TV is not exactly true across the board.
You can read just about any of the old magazines dealing with network administration and such to find out that Windows XP actually is slower than 2k on the real world bench marks they put them through side by side. I have yet to see, read, or hear anything about MS dealing with that and making it so XP does what it saya when it claims it is faster than Win2k.
Almost like Intels claims of being faster than AMD for so many years only to find out that it was a crock after all and Intel ended up in a class action suite over it...
luck to you...