1)
http://www.tomshardware.com/us/
2) Never bothered with any reg cleaners all that much; I tried 'Reg Cleaner' a ways back, but ultimately I 'format & reinstall' (windows mantra™)
3) Crysis is pretty demanding gfx wise. That spec. is better than mine - amd athlon 64 X2 dual core 3800+ 2.01Ghz, 2gb ram, nvidia 7950gt 512mb.
Ram, gfx memory and cpu speed are where it's at. Though I'm told 32bit windows will only support a maximum of 3gb of total system memory, including RAM, GFX RAM and any other memory on your mobo or sound card etc. Don't bother with a gfx card with less than 512mb of memory these days. Intel seem to have the edge over amd, though I stick with what I know (amd) for the same reasons as you were asking about cpu speeds
Start with a decent mobo (preferably one that can use 2 or 4 cores these days) with space for lots of RAM and PCIe (gfx slot - agp is not so good any more). If you're building it yourself, there's never any point in getting the fastest cpu out there for a premium; apart from some of the uber pricey ones, the choice seems to be between clock speed and cache (some of the intels have 12mb cache
) and go with somewhere in the middle of the range or slightly above.
'puters are a minefield though... in six months you'll be kicking yourself because all the bits you spent your money on are now half the price and your home will ring to the cries of 'Why?! Why didn't I wait just a few more moths?'
