How can I change my default OS?

I recently made two partitions on my hard-drive to install Ubuntu and XP. My main OS is(was) Vista. I had Vista installed on C:, Ubuntu installed on D: and just installed XP on E:. Now whenever my computer boots it loads the only OS available on E:, which, as I've explained, is XP. I can't delete or format the partition while it's active, so I can't go back to Vista and I can't access my applications on C:(Which is obviously my main partition and has most of the hard-drive space).



How can I fix this?



Also, I've tried going into My Computer properties to change it. It's not in the list and I don't think I can system restore, but here's the startup file if that helps:



[boot loader]

timeout=30

default=multi(0)disk(0)rdisk(0)partiti?br>
[operating systems]

multi(0)disk(0)rdisk(0)partition(3)\WI?Windows XP Professional'; /noexecute=optin /fastdetectHow can I change my default OS?
I remember a program called boot loader - it might help you with Vista and XP... Google it and read all docs before using...



Hope this helpsHow can I change my default OS?
You have to do it in the BIOS. When you start up your computer press F2, F8 or F12 and it should let you into the BIOS. navigate around a little and maybe you'll find it
when your computer boots up push F12 over and over till a boot screen comes up it should ask the question ';boot from?'; and then a list of drives will come up
when you boot up try pressing F12 (or whatever it is that brings up the BIOS) and change the order in harddrive priority.