Sounds like windows wrote over your master boot record as it usually does when installed second on a dual boot system. What i would do if i were you is log in using the recovery console and reload (boot loader of choice here). Another option would be to edit the boot file in windows for more than one os. You should be able to find examples of this on google. Here is a decent guide to start with. http://www.geocities.com/epark/linux...w2k-HOWTO.html
Hope this helps.