Depends on the spec of your PC. It is certainly worth going somewhere (anywhere!) from Windows ME as even Microsoft now admit that it is not much good. They have stopped supporting it. I still use 98SE with no problems at all, but if you have a PC that will handle XP, go to it. I would use Pro rather than home though. Specs will be somewhere in the region of Pentium III or 4, 1GHz +, 256 Meg Ram +
In all truth you'll find no substantial improvement. Providing your PC is powerful enough to run it, the most you're likely to notice is that your PC loads a bit faster and is marginally more stable. On the downside it costs a fortune and you may well find you have driver and software problems you didn't have before. If you really wan't to upgrade then you will be much better off with a clean lnstall of XP - upgrading from ME will almost certainly give you problems for evermore.