Windows xp won't boot. Help!?

I have a Dell Optiplex GX280, with Windows XP SP3, and a little while ago, i was converting a video from Windows Media Player format to iTunes format with a program, i do not remember the name. The video was barely at 2% when the computer all of a sudden crashed, and now Windows won't even boot. I have a System Restore point saved just before i downloaded the program, so i was going to try to go into Safe Mode to access it. But, Safe Mode won't even boot, it starts the normal process, but stops at "multi(0)disk(0)rdisk(0)partition(1)\WIN… I have read online that the only possible way of fixing it from here, would be with the use of the Windows XP start up disk, which i do not have. If any one can help me with this problem, it would be greatly appreciated. Thank you.