dual booting ubuntu

Ok trying to install ubuntu 6.06 but seem to be having some trouble. I have xp pro on my machine. my hdd is divided into 2 partitions. 1 is 80gb for windows and the other is 158gb for storage, but for some reason the storage partition is where windows update put SP1(the files) ok now i am running ubuntu off the live cd so i can be on the desktop. When i try to install it detects my hdd and i hit manual partition. then i see the 1st partition then my other partition then one that is 158gb and says nothing is used. can someone please tell me how to install this without FUBARing my xp install?

You need to resize one of your Windows partitions. ubuntu needs some free space to install, right now all of it is used up by your two partitions.

What you probably see is an extended partition of 158GB and inside that extended partition is a logical partition using up the hwole 158GB

Use something like gparted to make some room somewhere.