Problems with my first DIY

[STT414]

So I put together a desktop for the first time this evening. Read all the instructions very carefully and everything, but now that I'm trying to start the computer up it's not working correctly. The BIOS loads up (although not on a reboot, only after being powered off) it will load the OS (off of my old HDD from my previous setup) however once the OS loads up the computer reboots w/o any warning or anything. I'm thinking this might be caused by one of the reused parts I'm using since I had similar problems with my last desktop before it completely died. Im reusing: Geforce 7900GS KO and the HDD & DVD-R/RW that came with my old desktop. I can safely assume that it is not the GPU, as I took that out completely and it was still doing the same thing.

I also tried booting from disk to try and install a fresh copy of windows on my new HDD however once it got past the "Windows is loading files" black screen, the wallpaper would pop up, but the installer never would, both with a new Win7 disk and a Vista disk I had previously used. I was able to run a Boot Disk utility successfully, and I checked several of the components with the diagnostic tools on there, all of which passed.

Here are the specs:
Pentium E5200
Gigabyte GA-G31M-ES2L (rev1.1)
OCZ Reaper HPC Edition 4GB (2 x 2GB) DDR2 800
Antec Earthwatts 430W
WD Caviar 320GB (WDC3200AAJS)
WD 200GB IDE (WD2000BB-22GUC0)
IDE DVD-R/RW (from old desktop, not sure which model)
EVGA GeForce 7900GS KO

Any advice would be greatly appreciated.

[Geek-9pm]

Putting together a PC can be a lot of fun. You are almost there.
I have built many PCs over the years. There is one thing I notice. Your are putting some stress on the power supply. Used Hard Drives and CD-ROM drives tend to draw more power as the get older. And a hungry graphics card.

You should start a fresh install of you Vista system with a good Hard Drive and a good CD-ROM. Use the built-in Graphics card. No USB devices.

Once you have a smooth, clean install, start adding hardware.

You have to start with a neat clean install of Vista. If anything goes wrong, start over again. Format the drive. No overclocking.  No extra hardware. You want a clean install right from the start.

[STT414]

Thank you for the advice. Strangely enough after posting here, I ran some more diagnostic tests and then I noticed that the BIOS was loading fully after a reboot for the first time (No idea why) so I thought I'd try running the Windows 7 disc again and it worked. It loaded at a snail's pace at the beginning but eventually picked up, and now here I am posting on my new desktop. Everything seems to be working fine now.

[Kurtiskain]

The reason it would reboot:

You changed mother boards.

When you change mobos, the old chipset drivers remain.

Windows tries to load them and "Shazam"....Blue Screen Of Death.

When you re-run the Windows disk, it will re-detect and install the appropriate drivers.