All the reviews in all the magazines say that if W2K meets your needs then pass on XP. All you are doing is inviting possible headaches and a new learning hill to climb . . . hoever it is not as steep as that for 98 users. W2K has all the same stability . . . and if everything you have works . . . you don't gain much of anything except eyewash whose beauty is subjective anyway.
But, if you want to play with XP and learnin, why not get a 2nd HDD and make it yours? If you install a mobile rack, then with two trays you can have sparate drives and systems that will never impact one on the other. Better than dual boot arrangements. (That is another option . . . but they are not fool proof either)