I’ve been having fits getting zenworks imaging to work with Dell Optiplex GX280s and GX510s. I finally came up with a solution that works 100% of the time.
Set the SATA drive to compatibility mode in BIOS, and use the BCM57_v753 boot disk. This is the only version that seems to work with the SATA drives and broadcomm driver reliably. There is a new version based on the 2.6.11 kernel that I’ve tested with a bit, but it won’t install the Zen partition or LILO on the SATA drive reliably.