I vaguely recall reading a 20GB limit, but... I could be way off base. You can definitely do more than 4GB though. Also, I don't recall if that 20GB number is per partition or per drive.
Isn't there an OS3.5 FAQ on the net somewhere? I'm pretty sure I found one on Google pretty quick when I was reading up on 3.5 and 3.9 OSes.
