Windows Vista MBR problem

[Accessdabbler]

I'm trying to help a friend over the phone. A virus infected a system file on his system and a virus scanner removed the whole file so now he can't boot to Vista. He also cannot locate his Vista CD.

So, we installed Windows XP on the system (it came with the computer with a free upgrade to Vista but he lost the CD) in a folder called 'WinXP' so that he could reinstall the missing system file, which we've done.

However, he can't get the computer to boot into Vista as there is no option to dual boot. The computer keeps booting to XP.

What is the easiest way to get a dual-boot option on the system? We just want to try to boot to Vista to see if it is working. If not, we'll need to go back to XP.

Suggestions?

[SHAAN]

You should try repairing the MBR with inserting the vista disk. In case you don't have the disk it's really difficult to boot now from vista. As you have install the XP after vista so, not possible to show both boot options as vista uses new Boot Configuration Database (BCD) to load the boot information whereas XP uses boot.ini file to load such information.