Looking for a CPU??

[Dudelive]

It has got to the point that my AMD 1900+ is a little slow due to the programs of today that I run, so here is my questions:

Pentium or AMD? no I am not a hard core gamer
How big a difference is it between 512KB and 1meg and 2meg L2 cache?
I also am wondering if it is worth it to go 64bit or not.

I know the MB makes a big difference also but since I am not into overclocking, just how big a difference will it make as to the MB?

Just for your info, no I ain't made out of money either so I am looking for the best for the dollars or second best.

I have looked at the 2 below:
Intel
640 / 3.2Ghz 2Meg Cache Socket 775 800MHz

AMD
Athlon 64 3500+ 512KB Cache 2000MHz


Thanks
Dudelive