I had posted in the other thread, but in case you missed it.. For your problem, you are not going to want to use system restore. More than likely it very well may unleash more spyware onto your computer because a great number of spyware contaminate your system restore files.
But, if you still feel you want to. Here's what you can do to log in as administrator.
Reset your computer, and try to boot windows up in safe mode (press shift+f8 towards the beginning) and it should take you to the menu. If it doesn't, you can always trick your computer into it by hitting the reset button about 15 seconds into loading. Then let it load up and it'll tell you windows did not finish loading last time. Want to start it up in safe mode? Not the best way to do it, but it works.
Then it should take you to the login screen with your different accounts. Administrator should be one of them. Click on the administrator picture. If it asks for a password and you already tried all of them that you'd have set for it. Try: "password", "admin", (computer company/model ie:) "gateway" "presario" "compaq". If those don't work.. Well, there are always ways to crack it.
If you have your windows xp install cd, you can boot your computer off that, run it in recovery console mode and overwrite the password file.
Recovery console mode may have a password set, chances are it's the same as your admin password. To crack it:
Read the following, the following is an excellent link on how to crack admin passwords. It also gives you links to boot programs you can use which all do the trick. I've used Astranami, EBCD, pro tools, and they've all worked.
One last note though. Even if you do get into the admin account does not guarantee that you'll be able to do system restore. It could be that system restore is disabled (you can disable it in control panel under advanced system settings. System restore wastes ALOT of space, so sometimes it gets disabled to save space. If it's disabled then it saves nothing and would have no restore dates to use.
There ya go. Hope that explains it.