Browneyes, wasn't trying to step on your toes, just agreeing.
Upgrading Windows tends to just perpetuate problems from previous installs. It's always better to start clean.
I have some problems with the XP licensing, and we have had problems with XP and installing older software. Even Office 2000.
If you were purchasing a new machine which happened to have XP on it, I'm sure it would be fine. Again be careful with licensing. I have heard, although I'm not certain of this because while I am a programmer, I'm not responsible for keeping our software licensing current in our office, maybe someone else can confirm that the new Office XP is licensed for a year, and has to be renewed, which is a big change. I know that I had read that they were going to do that with XP itself, but I believe that got dropped.
For what it's worth, you probably should stick with ME. If you are having problems, the best solution is usually to re-install from scratch, as many problems are related to junk that is left in the registry and all over windows.