I swapped processors in my desktop from a Pentium E2140 Allendale (previously overclocked from 1.6GHz to 3.2GHz) to a new Pentium E6300 Wolfdale (now overclocked from 2.8GHz to 4.0GHz). The new chip is a good bit faster and should run more efficiently at 4GHz than the Allendale did at 3.2GHz. Besides that, my motherboard's actually not compatible with this particular Wolfdale, but I'm lucky of course that it supports older Wolfdales (some E8000's, E7000's, and E5000's). It runs; I'm missing various options (Virtualization, SpeedStep, proper temperature readings) but it still runs, even now that I am running it at FSB400.
I'm thinking of picking up a Radeon HD 5770. Some games are moody since I only have a HD3850-256 in this PC. Other option/thought is a HD 5750.