Computer hardware upgrade?

[Cyren]

Hardware geeks only would care about this stuff...

Currently:
Athlon XP 2800+
nForce 2 mobo
Radeon 9800 Pro

Very nice setup... when I built it two years ago. Starting to show it's age.

Proposed:
Athlon 64 3700+
nForce 4 mobo
Radeon 1800xt or nVidia 7800GT

This upgrade would cost me about $600 but I feel it would be pretty much 2x the speed of my previous setup. The radeon card is a little faster but quite possibly louder and hotter which is a downside. Also the nVidia card is a little cheaper and supposedly very overclockable...any thoughts?