I just selected "workstation" and the program says "not enough space". The free disk partition is 1.5 GB. The reason for this is: /boot was mounted on the big partition / was mounted on the small partition (in disk druid all looked normal)
I was unable to replicate this problem in the final release of 6.0.
I had the problem with the final (ftp) release. The disk is an IBM DCAS-34330 (4 GB). The first partition is NTFS with 2502 MB. I tried to install RH 6 in the remaining space.
This issue is resolved in the 6.1 installer.