What motherboard drivers did you install Nvidia's latest offical 3.13's? Also what ide drivers did you choose upon installation the SW ide, the in the box, or did you stick with Microsoft's default driver? Some poeple have issues with the sw ide. The "in the box" are just Microsofts drivers with ata 133 support.
Have you tried running the hd off of the sata controller instead of the ide? Another benefit of setting it up on stat is you'de have your opticals each on there own ide, faster on the fly burning

I noticed you've got 1 512 stick of mem and 1 256. You do have them installed in the dimm 1&2 sockets/single channel mode? I'm not sure if running 2 different size ram's in duel channel mode would cause any issue's. Also did you set the timings manually to match whatever the slower of the 2 sticks are?
I'm just throwing out a few idea's
