It sounds as if you have a corrupted boot loader. This is essentially what tells your PC to boot into Windows each time you start it up. To fix this, insert your recovery disc, and restart. It there is a prompt somewhere on the screen asking you to press a key to boot from the CD, then do so. A screen should appear saying "Windows is loading files." After it loads, follow the on screen windows until you reach the screen that says something to the effect of Automatically detect and fix problems. It should repair itself. I haven't done this in a long time, so please forgive me if it does not work.