cannot find O/S in new computer

Hi, all,

I just ordered a Dell from online and the O/S of the new PC is vista. I tried to do the participation for the big hard driver under Vista by using the vista disk management (shrink volumn, etc...). After Participation the O/s is under drive # C and I got some extended participations under the Drive # D, E, F.

However, when I tried to reboot the PC the O/S is not there anymore. I can still see my extended participated drives, but the primary drive C: is gone, although they are all under the same physical drive. I tried to recover the system by many methods but unable to find my o/s and drive C: back.

does anyone now what the reason is and how to fix that???

Thanks and have a great weekend!