yes, the i5-580M will work, and I would suggest it over the i7-640M. Not only are the benchmarks close, but the i7 may not even run properly in your system. The i5-580M is pretty much the best option. Agreed! I did some more research and came up with a similar conclusion. I ordered the i5-580 from a guy on ebay last night for $99 shipped and have the RAM on its way from CedarPC.com (only $55 shipped!). Im going to benchmark with the following tonight and will post 'before' scores and then will swap the drive to the SSD, retest everything. and then do it again once the parts show up and are installed. Success! My PCMark 07 score went from 1551 to a very acceptable 3213!
After first installing it still read as an i3 and I thought I'd have to reinstall again, but after a quick uninstall of the processors in Device Manager, the system reboot, installed new drivers and was good to go!
If anyone is thinking of doing this, I think we both can tell you its totally worth it! Kinda sucks hitting the brick wall that is the video card though O well !