Having trouble with installers

I just built a new computer, the specs are in my signature. I took the hard drives from my old computer, an 80 GB and a 200 GB. After installing XP and beginning to reinstall all my games and programs, I quickly found that many installers were "corrupt" and Windows wouldn't run them. One error message I saw a lot of was "An I/O error occurred while installing a file. This is normally caused by bad installation media or a corrupt installation file." Some game installers(Halo for example), had an error where a window would pop up during the install saying something about Windows finding a problem with some temporary installation file. I tested some of the installers on another computer, and redownloaded them on the new one, and I have verified they are not corrupt, so the problem is in the new computer. I also experienced a few BSODs, which gave me an error about a "machine check exception."
Something else of note: The hard drive that I installed XP Pro on had XP Home on it before, but it was a Dell version. When I first put the computer together, the bios would get to the point where it should boot to the drive, but it would simply stop and sit there. When I went into the boot menu and tried to boot to the drive, it said there was some kind of error booting to it. I finally determined this was because of the Dell version of Windows I was using, and went to get XP Pro. After installing XP Pro(which worked without a hitch) I began to install things, and that's when all the fun began. After some time of messing around in Windows I finally decided to try out the new version of Kubuntu, which I had burned to a disk earlier that day. I checked the cd and it was ok, so I began the installation. At one point in the installation, it suffered from some nasty error and stopped installing. I rebooted and tried again, this time my moniter suddenly gives me an "out of range" error. That was the end of my attempts at installing Linux. A little while later, I learned that bad ram could possibly be causing some of my problems, so I removed one stick of ram and rebooted. Now, I got the same problem I had earlier of the bios just stopping and the drive being impossible to boot to. I switched out the one stick of ram with the other, but it had no effect. I replaced all the ram in the original configuration, and made sure all wires were plugged in properly. Still wouldn't boot. Finally, I got fed up with the whole mess and decided to put the hard drives back into my old computer and reinstall XP Home on the drive, so I could at least use my old computer for the time being.
At this point I should note that I know the power outlet/strip that I am using is ok, as well as the hard drives(because I am using all of those things for my old computer again right now, and everything is fine). Here is a link to my power supply: http://www.newegg.com/Product/Product.asp?Item=N82E16817159056, which I believe is plenty good. Does anyone have any idea what to do?