I don't think it is directly related to the harddrives themselves. I have a couple of 30GB drives (from the same batch) in different machines. On some machines, the kernel update freezes the machine, while on others, it works just fine. With identical harddrives and wiring. I'd say it has something to do with the chipset on the motherboard.
I have four machines running 9.1 here. Three (slightly older ones) work fine with the new kernel (one Asus Centrino Notebook, one older P4 and a Duron box). With the fourth one (Athlon64, ASUS K8V) I experience the problem. My first thought was, that it could have something to do with SATA, as the three running ones don't have it. On the other hand, if You have problems with older machines... But I agree that it probably has to do with the chipset though. Regards, Christian