You shouldn't need a partition with DOS to install Linux to. During the Linux install process doesn't it have a utility to let you repartition your drive? If you want a Linux-only drive, delete all the partitons on your drive and then create a new ext3 partition (or two or three), and a swap partition. I thought RH always had an option that would give you a "recommended" partition scheme too. If RH7 doesn't let you do that, maybe you should get an updated version of RH, because almost certainly, newer versions do that. By "DOS partition" I assume you mean FAT32, but installing Linux to a FAT32 partition = very bad, because FAT32 partitions don't store file permissions like ext3 or reiserfs or xfs partitions do.