Partition Magic HD "geometry" error

I've built a system, and installed a Seagate 200GB HD and WinXP. But I could only create a 137GB boot partition (with Seagate's DiskWizard Starter) since pre-SP1 XP doesn't support anything larger.

When I try to access the partition with Norton Partition Magic 8.01 (DiskWizard doesn't support stretching), I get a strange error saying something like "Disk 1 has partitions created with a different geometry. Please delete your partitions."

I know I can just create a second partition to fill the space, but I'd like to be able to use Partition Magic. So far Seagate wants me to talk to Norton, and vice versa. Does anyone how who I can get PM to accept the partitions I have?

-Thanks! matthias