Formating an external disc except one volume?

[Krister Ekstrom]

Hi folks.
I have an external 1 terabyte hard drive that i want to format to use  
as a time machine backup disk amongst other things, Now i wonder how  
do i format the drive, but leave my 32 gig fat partition untouched and  
possibly extending it somewhat? I tried looking at the help, but i  
didn't get any wiser as to how to use the disk utility to format disks  
in the way that i described it with VO, so if anyone could give me an  
answer i'd be very happy.
Thanks
--
/Krister