Always Get / Make Restore CD
As is normal when I come home for a few days, I got a call from someone whose computer is infested by malware (possibly Antivirus XP 2009). I said right up front, “I’m not driving to your house, and I might not get time to work on it if you bring it to mine.” So I was talking the person through getting Windows XP back to a usable state. There was no restore CD, it had the restore information on a partition on the hard drive. And the person hadn’t known that getting a CD would be necessary, so there wasn't one available.
If your computer gets infected with anything—virus, trojan, spyware, or whatever—you can no longer trust that disk partition to be clean and pure. For that reason, always make sure you obtain a restore CD or DVD. My most recently-purchased computer came with a single-use application to burn the restore information to a set of CDs or DVDs, so I used that. If I ever wanted to re-experience the pain and frustration that is Vista, I could go back to what I had when I bought the PC.
If your computer is older, or if it did not come with this software, you should get on the phone, NOW. Call the computer’s maker and request a restore CD. It may cost you some money, but get one anyway. The person on the phone will try to convince you that the restore partition is enough. BZZZT! Wrong answer. If / when your computer becomes corrupted, it is too late to rely upon the restore partition, with its then-unknown integrity. Be pleasant, but firmly insistent on getting a CD.
You may be able to simply burn a CD of your restore partition (and hope it is not already corrupted). I have not tried it, so you alone are responsible for the results.
I have no idea whether the restoration was able to return them to a clean system. I got off the phone and went back to cleaning up and updating the XP desktop here. After six months' absence, it really needed some work.