Hey all,
My current specs are:
AMD Athlon XP 2000+ (1.67ghz)
ATI Radeon 9800pro
768mb RAM

I'm thinking about upgrading my Processor (i know my GCard isnt so good
either, but it at least does DX9, and i'm also going to increase my
RAM), but i don't know much about them - plus i only have a limited
budget. What's the best CPU i can get (for Source) for £100 or less?
i've been looking at an AMD Athlon 64 3000+, but the clock speed is
only 1.8ghz. would this be a big improvement? is this CPU the
equivalent of, say, a P4 3ghz? (oh, and would i be best to then get the
64-bit version of Windows?)

thanks for any help!

There are folk that can help you but you'll need to tell us what mobo you
currently have and whether you'd want to keep it or replace that too.  I'm
guessing that for £100 you'd want to keep it in which case it's simply down
to the best CPU that the mobo will take.