Whenever I've set my PC up for dual booting in the past, I'd have one partition for NTFS, one for ext3, one swap for Linux and a FAT32 partition for common storage between linux and Windows. I'd put all my music and videos in there, so I could watch them in either OS. I didn't want to mess with NTFS in linux, or use FAT32 for my Windows partition. If I couldn't do that anymore, it would really suck. I'm not workin' for big bucks yet, so two computers isn't really something I'd want to invest in.