Also, you could repair your windows MBR and start over. You'll need either a System Repair disc (which you hopefully made previously), OR you can use the windows 7 install disc.
1. Boot from either disc.
2. Select your language
3. On the Install screen, click "Repair your computer" (this option only appears with the install disc - a system repair disc will skip this screen).
4. The system will locate your windows install, make sure the top radio button ("Use recovery tools ...") is checked and click next.
5. Select "command prompt"
6. Type this at the command prompt:
This will give the boot control back to the windows loader, and your machine should boot normally. You can delete the backtrack partition and try again. Be sure to go to control panel and make a system repair disc (if you haven't) and create a backup image. You can experiment with Linux with confidence knowing you have a backup of your entire system. Anyone who uses Linux has been in your shoes!