It seems to me, the least problematic is to clean install XP. If you have an
upgrade version of XP, you will be prompted to insert your ME disk to prove
eligibility for the install. Many posts concerning problems, to this and
other groups, are directly related to remnants of their old OS. You bought a
new OS, why not give it a fair chance to show you what it can do?
Although many people will tell you that formatting and installing
cleanly is the best way to go, I disagree. Unlike with previous
versions of Windows, and upgrade to XP replaces almost
everything, and usually works very well.
My recommendation is to at least try the upgrade, since it's much
easier than a clean installation. You can always change your mind
and reinstall cleanly if problems develop.