use partition magic to make ur windows 20-40GB smaller, and then knok off another 1GB for swap space. use partition maging to format the big partition as ext3, and then format the small 1GB partition as linux swap.
when installing ubuntu, set it to install on the ext3, and use the other one as swap space. tell it not to use ur windows partition.
ubuntu works fine with my dell utility partition. if, like mine it is a partition you can boot to, you will not be able to boot to it without modifying grub.
when installing, allow grub to be installed onto the mbr. if all goes wrong, you can always boot off the cd to recovery console, and "fixmbr"
hope this helps