I switched to Ubuntu ages ago on my Dell XPS 1210 laptop. But I did go down the route of dual booting at first. Soon after I stopped using Windows for everything except virtualdj which simply would not work emulated or virtualised under Ubuntu. Then a while back I found my 120gig hard drive getting quite full (unknown to me that I was backing up to the same hard drive at the time) so I deleted the c:/windows and c:/program files directories. I had changed my /home/ian directory to map directly on top of c:/document and settings/ian forrester/my documents/, so if I did boot into windows every document and media file would be accessible to me under Windows XP/Vista. So for about year I've been walking around and using the laptop with a small ext3 partition and a huge ntfs partition.
Everythings been great, but I sometimes noticed my laptop getting slow and sometimes hanging. I looked into it and it came down to two things. One Flash is still badly written for gnu/Linux and kills the browser if loading a large video or attempting to use the webcam. But this seems to only effect the browser environment, so sometimes I need to force kill firefox. Number two is Fuse/3g, which allows Unix operating systems to read and write ntfs formatted file systems. This was great at the start but I noticed Fuse will be eating all my CPU resources. So I put out a pled for somes software like Partition Magic which can convert a drive not just format. Some advice came back, but generally people said copy the whole drive somewhere then format it and put it back.
So today I did using a spare 100gig hard drive and the Ubuntu live CD. It all went to plan but a couple of points to remember! Chmod all the files to match nobody:nobody so later on you can access the files and change the mod to yourself. As default Fuse makes files on a ntfs disk root:root. This is fine till you move them to a ext3 disk and those permissions take affect for real. Also check the boot flag is assigned to the correct drive.
So now with NTFS gone, its goodbye Windows for good now.