Nodijo

Hi. Please forgive me if this is the wrong place to post this, I searched and read the other threads before posting and didn't see anyhting in the other topics either, although being new, I'm still finding my way around. I am new to Vista, I must say I really like it, if I could get myt problem resolved, I'll be VERY happy. I am a Graphic Design major, so my computer is my lifeline so-to-speak. When my son did this build for me we did it in stages and I'm pretty proud of where we are. However, huge issue for me- Vista will boot just fine IF I leave the original installation disc in the drive, if I remove it and try to boot it, I get the message in DOS "BOOTMGR is missing press CTRL+Alt+Del to Restart" this is very annoying. Anyone know how to 'fix' this problem or do I just shell out $60.00 to the computer techs that said they could fix it? My son told me to check here first.
My system is:
Built by my son "Mr.B"
Windows Vista Home Premium x64
ASUS P5N-E SLI
Core2 Duo E6300
4Gb XMS2 800
(2 150Gb RAPTORX in RAID 0)
250Gb SATA2
(2 eVGA 8800GT in SLI)
Antec SmartPower 500watt
Acer X191W widescreen monitor