No, Windows ME is not the same as 2000. Sorry.
If you want to upgrade to XP for cheap, you can find Windows XP OEM licenses by searching on Pricewatch
. Then all you need is to find an install cd from someone you know, or buy one off of ebay for a reasonable price. Oh, and in case you're wondering, that's perfectly legal (it's the same thing a company that builds computers would do).
Trust me, though, it's worth it!