I'm looking into building a new PC for myself...and was wondering if an athlon 64 processor is really worth the extra money. I currently have an AMD 1800+ and saw that any AMD 3000+ and above is fairly cheap. Is the 64 worth an extra $150? Also, this would mean i'd need a new motherboard and all. I'm assuming i should switch to PCI-e in terms of gfx card from my current AGP4x? And lastly, does windows xp professional compatible with a 64-bit processor? thanks for the help!