I recently bought a 148 Opty, Biostar T force mobo, and a 350 psu--all for $200 gotta love Newegg. Everything runs great, The problem is that when I try to unplug the extra IDE HD and a DVD drive from my computer it wont load windows and instead I get the message that follows: " Boot CD: Error Failed to boot from CD, please insert CD".
I have worked on the BIOS settings, but I think that the problem lyes within the SATA HD which tells the MB that there are components missing. I dont know if this is the case, and I am probably wrong but I have run out of theories and I deas how to fix it.
Once a gain everything runs great with the three drives plugged in but once I shut down and unplug them there is no way on earth to boot windows from the lone SATA drive.
I only need one SATA HD on this computer and I want to transfer the IDE HD and DVD drive to my second computer.

Thank You guys for your help!

Sorry, but your post is very confusing. How many computers are we talking about? Exactly what is connected to each computer (model numbers of CPU, drives, motherboard, etc)? What drive(s) is Windows installed on? Is it Win XP SP2? What is the BIOS boot order set to?

Yeah sorry, I will try to explain better.
I used the old SATA HD (Western Digital Caviar 70 GB) which was in an old computer (Sempron 2800 with 1gig PC3200 ram on a ECS mobo) and had Windows XP SP2 on it, to build the new computer (148 Opty 1gig PC3200 on a Biostar TForce 6100-939). When I tried to use the old SATA HD for the new computer it did not boot up, but I recognized this problem because it happened often on the old computer when I unplugged the DVD drive or the other IDE HD. I then connected the three: the IDE HD, the SATA HD, and the DVD Drive to new computer; it booted up immediately.
Now, Im running the new computer(with the three: (SATA,IDE and DVD)plugged in) as Im typing this and its rock stable, the trouble is when I try to shut down the computer and remove the DVD drive and the IDE HD leaving the SATA HD alone. When I boot up on the SATA HD alone it does not boot up, not until I plug the other two drives back.
I hope this helps, its just really weird and hard to explain. Thanks Again

You always need to re-install Windows when you upgrade the motherboard (because it needs different HAL or "Hardware Abstraction Layer" files for the different hardware on the new MB). Did you re-install Windows onto the HD once you connected it to your new MB? If not, go ahead and do that.