Wow all of thoese steps that people gave you wont do the trick.
System restore is really only meant for going back a few days at a time. And Safe mode wont give you the options, and then going into add/remove is tottally the wrong place.
So here is what you do, since you seem to want to format your hard drive, click stat, my computer right click the hard drive and click format. And then follow any directions it gives you after that.
In order to reinstall windows, you must have the CD that came with your computer or one you may have bought seperate from it. If no CD came with the computer and you did not buy one, then you were supposed to create the cd from a program on your computer. it should be located in the start menu in the all programs. In any case to obtain a cd you can call the manufacture of your computer and they will send you the cd, it shouldn't cost you anything. it didn't for my sister.
Once you have the cd, put it in your computer, turn the computer off and then turn the computer on and let the cd run. If the cd those not start, get back to me, depending on your computer, you might have to go into the bios menu and switch it to read from the cd first before the hard drive.