Pitfalls and Issues Surrounding NT40 to Srv2003 Upgrades

I am desparately trying to upgrade a domain controller to W2K3 server from NT40SP6a. It is a relatively new server hardware and has a RAID array with an 8GB OS partition setup instead of the normal 4GB partition. NT installed just fine and runs great under this setup. When I attempt to install W2K3 (upgrade) from the CD the machine reboots and goes into the W2K3 setup feature and the BSOD’s on me saying somnething about checking my disks. QUESTION: Since NT was ALREADY running fine under the 8GB OS partition, and W2K3 will have no problem using it, why am I getting the BSOD’s? ALL HELP APPRECIATED…. Thanks