Windows XP 64bit system memory question

Ok i have been hearing random things about the 64bit version of XP. First off when ever i go to Newegg or zipzoomfly or tigerdirect i never even see a 64bit of XP listed for sell. So im wondering if its called WinXP Pro SP2 since that seems to be the most common. Secondly i currently have 2gigs of ram and i want to upgrade to 3 or 4gig of ram, I DO NOT want Vista at all until they fix most of their issues with that mess of an OS, it just reminds me of Windows ME maybe even worse. Anyways would any version of XP support over 2gigs of ram?

System Spec - Intel core 2 duo e6700 2.67ghz, ASUS P5B-E LGA 775 Intel P965 Express ATX Intel Motherboard, Corsair TWIN2X2048-6400C4 2GB Kit DDR2-800 XMS2-6400 Xtreme Performance, Thermaltake W0117RU Toughpower 750W Power Supply, BFG Tech BFGR88768GTXOCE GeForce 8800GTX 768MB 384-bit GDDR3 PCI Express x16, Winxp home sp2

I thank everyone for their time in reading this post.
~Vipboy28~

i'm running XP 64-bit with 8 GBs of RAM. The max XP 32-bit supports is 3-3.5GB i think

^True. It runs fine, BUT there are still problems with it. I have problems now with the latest GPU drivers and sound drivers after SP1 update (worked fine before). there are still software incompatibilities. Also when some thing dose go wrong it is easier to recover imo, BUT if something goes really wrong you are fried.