hi, i've installed xp pro on one partition on my hdd (it worked). then i installed windows 7 RC on another partition. but when i start up the pc theres no dual-boot screen that asks me to choose an OS. Windows 7 starts up. I have an ASUS M4a78t-e motherboard on my self-built PC.
If memory serves me correctly, you're supposed to install the NEWER OS first, since the older one has no knowledge about the newer OS.
Dailun is correct and you should still be able to see all data on other partition so I'd find a way to save anything important from it. boot from your original disc and try to recover your partition. http://support.microsoft.com/kb/307654 I know theres a way to modify the boot so it looks at the other partition too but I dont remember the code maybe someone will find a link quicker than me ...