Dimension 4600 Not Starting

[EXCellR8]

I reformatted an older Dell earlier and now I'm having issues with the RAM. It had two sticks of 128MB DDR RAM (PC3200) and I tried adding a single stick of 256MB of the same type. After the computer recognized that there was a change in physical memory I went to load XP and I got a fast blue screen. Now, the OS will not load at all even with the original memory configuration (128x2) reinstalled. I hate Dells, have I mentioned that?

Also, when i try to boot into Safe Mode it stops loading drivers at agp440.sys if that's any indication.

 

[EXCellR8]

Alright so I didn't exactly figure out what happened with this but it had something to do with the OS or the HDD I believe. I swapped out the drive with a spare 40GB I had lying around and did yet another fresh install; all seems to be working now. I have no idea what caused startup to hang but I did notice that when I tried a repair install on the original drive, setup also hanged when it searches for previous installations of Windows. When I wiped the disk clean and formatted it as a slave/external drive, it worked fine...