extended dos partitions

fdisk /mbr--------------------------------------------------------------------------------
to remove the boot loader (LILO? or doesn't mandrake use a different one?). I don't see why this would make your RH install fail though. I'd remove those FATpartitions if you don't need them too.
http://www.dc.turkuamk.fi/docs/mdmanual/mdkuserguide/007.html

fdisk will not delete the extended DOS partition until ALL logical drives are deleted.

What do you plan to do with the space left on the drive after deleting the extended DOS partition?

If you wish to add the space to the Primary DOS partition, you will need to use a utility such as Partition Magic to re-arrange the disk space.

If you just wish to free up the partition, there are links to utilities to remove Linux partitions at both www.fdisk.com/fdisk
and www.bootdisk.com

Chas