If you can't see the initial startup messages, try hitting the Del key to gain entry into the BIOS as soon as you hear the beep. If that doesn't get you in, try F1 - and then F2. It's almost always one of those three.
Once you're in, disable Quiet Boot; you always want to see all the wording that takes place during POST and boot. Also look for the page to set BIOS defaults, and do that. Also set the CD drive first in the Boot Priority.
Zoron is on the right track. File corruption like you've been experiencing, is frequently caused by hardware failure.
The first suspect for me is always the power supply. Secondly, a poorly installed cpu (processor) - poor heat transfer from it to the heat sink allowing a dangerous heat buildup and cpu shut down. Thirdly, a flaky memory stick. Fourth is the hard drive.
Don't get yourself in a panic (you sound inexperienced). You can troubleshoot this stuff methodically.
I make the assumption that there is a friends' comp you can work at. Download MemTest, and make a cd, and run it on your machine at least 4 hours. Look for errors to show up on its' working screen. This will eliminate the ram as the problem if you see nothing written.
Next, uninstall the hard drive and "temporarily" hook it up to your friends unit (just unplug his drives' cable & power and plug them into yours). This is also assuming you're both IDE. Let us know. If you can get this set up, try the install. If it works, the problem is a piece of hardware in your tower.
If you've passed the ram, and now the hard drive, you should find someone who knows what he is doing to check the cpu install. If that's okay, replace the power supply.
When you've found the problem, put your unit back together and reinstall. Prompt the install program to delete the partition and then recreate it; format NTFS and run the XP. Hard drives can't be swapped between dissimilar machines.
Good luck!