Error loading operating system

I installed new mobo, 2 GB ddr3 RAM, CPU, and psu per recommendations from you guys earlier this week (http://www.tomshardware.com/forum/287437-31-upgrade-mob...) and got error loading operating system.

Since it was a hard drive from an earlier build I reformated it, installed XP and for the first restart on the installation it got the error. I update BIOS and ran chkdsk to fix the 1 error it found.

The HD is IDE so I'm thinking it just isn't compatible with this setup. Any other ideas?

Thanks