I like XP since it is stable and based on the NT code rather than DOS
I went back to ME and I found that ME is not as stable as XP SO I am back to my XP
Just buy the XP upgrade , do a clean install after you back up your data ( You can use Norton ghost to back up your entire drive to CDRs or another partition of your drive , It is easy to restore your data after you get XP and Norton installed )
Win XP set up will ask for proof of a previous OS, Just toss in you Win ME or 98 full version cd, and follow the prompts