[G4] PowerBook G4 titanium

[Feldave at aol.com]

550mhz PowerPC- powerbook
512 MB sdram
20gig hard drive- original IBM
OS-X 10.3.9

I need to upgrade my hard drive.
I'd like to get a 60gig.
I'm assuming that anything faster than 5400rpm is to hot for this machine. 
True?
8mb cache buffer seems most common.

I would like some recommendations on what brand/type of hard drive to buy.
Are my assumptions correct?

Thanks,
Dave