XP keeps rebooting and will not Repair

Hello,

I downloaded what I thought was a free virus download and it currupted another system that using XP and its currupted a file and now I cannot get back into Windows. At start up it just keeps rebooting itself. I have tried to choose turn off auto reboot after system failure and it reboots again to the OS options. I have gone into the advanced settings of F8 and tried all options there which include: safe mode, samode networking, bios, debugging, restore, etc... and when I chose one of those options it just reboots back to the OS options. So I put the XP cd in with an attempt to reinstall windows or repair. It tells me that i8042prt.sys file is currupted and set up cannot start and to restart; so im back at square one. I even tried loading the XP disc and using the repair option and Windows XP CD is not repairing. Any other suggestions here, I need step by step if possible. i WAS going to try and install a repaid and recovery software to a disc from a website and load that cd on the computer in order to repair. Will this work? Or can I download a virus software to a cd and run that by booting from cd? will that fix?

PS, I get to the part in the Setup and press "R" then i come to a DOS prompt that says:

Type EXIT to quit the recovery Console and restart the computer.


Please help if you can!