h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Maolmuire has a point. However, installing Linux is not necessary. Linux live CDs can be used to salvage data even on a catrastrophically failed Windows computer. If you've ruined Windows to the point of not even booting, the below is one recourse. It is potentially overkill but it is far simpler than the weird hacking necessary to restore Windows, and it is permanently effective.

Set your BIOS to boot from the CD-ROM and insert a KNOPPIX or MEPIS disc, or any other boot-from-CD Linux distribution you fancy.

Most of them should be able to read NTFS partitions, and all can read FAT32. This means you'll be able to see what is on your hard drive even if it has a broken Windows installed on it. From here, you should be able to browse to any directory on your Windows machine. If you're willing to take the time to try this method, you're probably intelligent enough to discover the correct commands for properly mounting your Windows partition. But an example would be: "mount /dev/hda1 /mnt/hda1"

Once you have access to the Windows part of your hard drive, you can launch a cd burning program. My favorite is K3B, but there are others. I launch it as root, Unix's version of "Administrator", just to be sure I have access to everything on the hard drive(s) in question. Back up the files you want onto CD-ROMs and then reboot and reinstall Windows.

Once you have Windows reinstalled, install the free ZoneAlarm firewall, the free AVG anti-virus software, and the free Mozilla/Firefox web browser and the Mozilla/Thunderbird email client.

Whatever it was that ruined your computer the first time around won't be able to touch you now. Internet annoyances will practically vanish, and email viruses will become a distant memory.

And since you have a Linux live CD now, why not poke around in the operating system to see if you like it? I have found the Linux environment to be much simpler and elegant than that of Windows. That's just one guy's opinion, but you'll never know what it's like until you try it yourself.