Need help reinstalling Windows XP - Don't have original Setup CD, "system32\config\SYSTEM missing or corrupt"?

My Gateway laptop (purchased a few years back from Best Buy) was running XP but got infected with a virus (Antivirus System Pro) and then wouldn't boot back into Windows in any mode (Safe, Normal, etc.), it just kept looping back to this Advanced options page, so I couldn't run any anti-malware. Sadly, I... show more My Gateway laptop (purchased a few years back from Best Buy) was running XP but got infected with a virus (Antivirus System Pro) and then wouldn't boot back into Windows in any mode (Safe, Normal, etc.), it just kept looping back to this Advanced options page, so I couldn't run any anti-malware.
Sadly, I DO NOT have an XP setup CD (Don't recall ever getting one, though I have a plastic packet with some sort of code on it, maybe registration?). So to try to restore the system off the hard drive using F11 key and (because the "non-destructive restore" wouldn't work) a System Restore with Backup. That seemed to run fine, but after windows started opening, the screen went black and a Windows Message comes up saying "The system is not fully installed. Please run Setup again." I tried doing another System Restore, same thing. Tried "Last known good configuration" and got the "windows\system32\config\SYSTEM missing or corrupt" message saying to insert the Setup CD and push "r" -- but I don't have the CD.
I do have another computer that works. I'd hate to buy a new OS and not sure if that would work or is necessary. Can I download XP installation to CD from microsoft, or try something else (maybe in Advanced Options, Boot Menu or BIOS settings -- the things I CAN access) to get the system to fully install? I'm not very tech savvy so could use detailed instructions. THANKS!!!
Update: One good samartan suggested I call a technician. Is this something I really can't fix myself?
2 answers 2