Some harddrives incompatible with intel iMacs?
According to this user's post
on xlr8yourmac.com, some harddrives might have a hard time inside an intel iMac, should you try to replace the one it comes with with a bigger one.
The problem seems to be that Disk Utility on the installation DVD-ROM can format external
drives (FW/USB-2) with the correct format (using GPT, the "GUID partitioning table"), but doesn't allow this on the internal drive. At least not with the particular WD4000KD drive the user was trying it on.