Internal drive speed for video capture

[David Crump]

I was wondering what is the minimum speed required for an internal hard drive for video capture without dropped frames?  I always hear that 7200rpm is best for Firewire drives, but does it make a difference if it is an internal drive?  I am just concerned that if I get a Canon ZR 60 it may not be able to capture to an external firewire drive.  If I end up with this problem, then my only other option is the internal drive.  With an older iMac with a slower hard drive, are my only options replacing the internal drive or getting a non-Canon Camera?