AMD64 or i386 ?

[Guardian]

hi,

I have AMD Anthlon 3800 [64-Bit]. So I have an Amd64 version of kubuntu on my 
system.

But I could'nt take advanteges of my Nvidia GeForce 7300 GS yet, I tried to 
install from source code by the file that I downloaded from Nvidia's site.. 
(I could'nt solve init system)

And the second question is; is there any advantege to use 64bit version of 
kubuntu than i386. I think to change my system to i386 version..

thank you for your sharings..