I would recommend the same if you have backed up all your required files. Don't install the latest windows on an old computer. It's best if you reinstall the original operating system and then have a good anti-virus installed later. If you are not sure how to do that, you may need help from an IT professional.
-Okay-I tried all those spyware busting systems and everyone want me to buy their program-they say free-they are not FREE!!~!-Now-the SCANS ARE FREE-but what is the good of scanning if they don't delete the bugs!!~I ask you?
If you ran superanti-spyware(Free edition) and it did not remove it chances are the $ ones won't help anyway. I would follow Jeff's advice. Back up what you want to disc and the reinstall Windows. This should definitely correct the problem.