Problem Solved. I'm just posting the solution for anyone else who may read and benefit. I have two external USB harddrives as well. I disconnected them and now the computer boots up fine. It appears the system was looking to boot from the external drives. In the BIOS, the boot order is 1...
I've had my computer for about a year running XP with 2 harddrives in RAID (mirror). My motherboard, Asus P5NE SLI, has the RAID controller built in. These 2 drives are my only drives (other than an external USB drive). I wanted to get rid of RAID and just have 2 regular drives and install...