I'm currently working on modding an old Optiplex GX520 to run several old games (1998-2000) I have for the sake of nostalgia. I'll admit that I'm very new to PC building and need assistance in finding compatible parts. The motherboard is a Foxconn LS-36 with a PLGA-775 socket, so what would be the best CPU I could upgrade to? Also in need of recommendations for a soundcard as none are detected.