How can I boot from my other partition?

[Guru]

I've got a 160gb hdd in my lappy which I've split in two, one half vista and once half xp.

Now since I installed XP it ALWAYS boots from the XP partition.

How can I chose to boot from the Vista one at times?

I know how to do it on two separate physical drives but not on two partitions of the same drive. Is this even possible?

Cheers,

G

 

[Guru]

none of the above working so far

F8 brings up the menu to chose the boot options, like the OS. BUT Vista is not listed

I'm stuck

Any more ideas?

Cheers,

G