Dual boot problems.

Today I bought a new hard drive, and an OEM copy of Windows 7 home premium. Installed the drive, and proceeded to install Windows 7 on the new drive. My problem is this. On the other hard drive, I have Windows XP installed, since installing Win 7, I do not get the boot screen to choose what OS I want to use, the system just goes straight to Win 7.

I tried doing the F12 boot menu, and chose the drive with XP installed, but when it tried to load , I got a message saying "NTLDR is missing, presss control, alt delete to restart" . IS there anything I can do, short of reinstalling XP?