XP & Vista dual boot issue

[Cheex]

I have XP and Vista in a dual boot setup.
I did a fresh install of XP. It was getting sluggish, also in preparation of my 2nd 1GB of memory, which I just received and I'm about to install.

The problem is that now I no longer get the option to boot into Vista, it just boots into XP no questions asked.
I want to know how to "reactivate" that menu. I hope I don't have to reinstall Vista.

How do I do that?

 

[Noema]

XP overwrote Vista's (newer) bootloader. See, when you install Vista on a computer that has XP's MBR, Vista adds XP to it's own Bootloader.

But XP, being older than Vista, can't possibly know of Vista's existence and thus simple overwrites the Bootloader.

Try Vista BootPro.

Oh, and don't forget to make a copy of the BCD before doing anything in case something goes wrong. (you can do it from VistaBootPRO).

 

[Cheex]

BCD Registry Missing/Corrupt

How do I fix that?

 

[Cutthroat]

Boot from the Vista DVD, at the repair screen it should notice the missing BCD and give you the option to recreate it, with XP as an option.