Snow leopard takes ages for me to boot as well - and I don't think it's the hard drive's fault. It drops a few messages on verbose mode, HDD light goes off, Wait, wait, wait, HDD light comes on and it goes to the desktop. I think it may have something to do with having two other Windows NTFS partitions on the same drive that it has to detect.

---

Asus P5KC | Q6600 3.02GHz | 4 GB DDR2 887MHz | 9800GTX | 1TB WD Caviar Black

Snow Leopard 10.6.2
Sleep | Vanilla Speedstep | DSDT

Everything you need can be downloaded here.

Leopard 10.5.8 | Windows 7 Ultimate x64 | Windows XP SP3