Are you in the US? If so, consider buying used components. I've picked up e8400 cpus for $40 and 2x2GB DDR2 for $30 off eBay. Very easy/cheap to upgrade your system to a lot more power that way. (A stock e8400 is going to be faster than a hugely overclocked e2180.)
Sad but true but the lowliest Sandy or better yet Ivy will blow any Penryn away.