Want to boot from a new hard disk with windows 7, keeping the old XP

Hi, I have been using windows xp, installed on a ATA hard disk. Recently I bought a SATA hard disk and installed windows 7 ultimate on it. I installed the new windows unplugging the previous hard disk and it boots ok. But now I don't want to switch from win XP to windows overnight, since it is a home PC and every one is used to the previous settings and all.

Now when I plugged in the old hard disk, there is no option to boot from my new windows. And the new hard disk's drive letters start from the previous one's last drive letter, where I want the new hard disk's 1st drive to be C:.

Is there any way to keep the previous installation and choose in boot time from which windows I want to boot from? Also how can I make my new hard disk's drive letters start from C:?

Thank you

The Windows 7 C:, will only show C: when you boot Windows 7.

To boot the HDD, use the One Time Boot Menu.

It worked! Thanks a lot... and sorry for being late, I got busy with some other stuffs in life..