Most HP systems within the past few years used ASUS mainboards. Best to find either an exact HP replacement or ASUS equivalent on Ebay and flash it to HP's BIOS, then use the recovery CD's. If you didn't do it that way, the restore CD's will be useless (pretty much every company, be it Gateway, HP, Dell, etc. has CD's coded to their own systems).
Intel Q9450 @3.2GHz, Gigabyte GA EP45-UD3P, 4 x 2GB G.Skill @4-4-4-12
Antec P160SW case (modded), Xigmatek 750w PSU
3x 500GB (RAID-5), , OptiArc 7200S, ASUS E818A3T
Creative X-Fi XtremeGamer, Hauppauge HVR-1800, Radeon 4890