try the linux version of fdisk (there is a small button to select it durring install) and use it. It is much more flexible and can work with other OS's - unlike the DOS version of fdisk. There is a bit of info on using fdisk here:
Some people also like using cfdisk, i don't know much about it but I am sure it is fine.
hth, if not let us know.
oh - BTW - lets keep this the only thread on the subject so as not to confuse people.