Don't worry about the partioning....Vista can help...believe it or not!!
For dual booting with Vista, use the shrink option in Administrative Controls (I think) in the Control Panel.
(It's only been a month and I'm forgetting the Windows stuff already!!!)
Defrag first....
Right click the drive you want to partition. Select Shrink.
Use as much space as you can....Click OK.
Reboot with the LiveCD/DVD in your drive. Follow your nose through the instructions.
When it asks about partitions, select Guided - Use available space (or similar_ - NOT manual.
The great thing about this puppy is that it will find the space you freed up, install to that space and then set up the boot loader to ask you if you want to boot Ubuntu or WIndows.
Ubuntu is default so , if you leave it, that's what will boot.
I dual booted for less than a day. Because Ubuntu could see my backup drive in NTFS, I ditched Vista real quick.
This Ultimate Edition 1.7 is great....I'm not going back.
Cheers