Vista - Dual Boot one C Drive Sata E drive IDE

Ok here is my question. Im not a tech guy so I dont want to do this if its
not going to work. My main C drive is a Sata drive and My E drive is an IDE
drive. I wanted to load Vista on the E drive and once all is said and done be
able to start the computer and have a choice of which OS I boot up to each
time. For I may not want to boot to Vista all the time or XP Pro all the
time. If I load Vista on the IDE drive will my computer still work fine. Will
i say be able to boot to vista on my E drive and see my other drive that has
XP Pro and all my files on it. Or will I have to go through a big ol process
to make this all work. I am trying all of MS betas and have the Office 2007
beta, office live beta and love them both and would really like to try the
VIsta Beta as well. But not if its going to mess up my whole system and I
wont have a choice which OS to boot to or if it will just give me a black
screen becuase if it does then I have no way of coming back here for help.
Your help and input is much appreciated in advance.

matthew