Yep.
In fact, I suggest you do what I did -- rather than keep all the VM images on the laptop HD, put the ones you don't use as often on an external FireWire drive. Plenty fast enough for normal VM use. USB2 is not too bad performance-wise, but since you've got FW on the Macs may as well use it.
I only keep the WinXP and Vista VMs on the MacBook HD. The rest are external. Having them external also means I can run them on other Macs (like the Mini). And it's only a couple of minutes to copy the VM image from ext to internal, so if I want to travel with (say) the Fedora image, I just copy it to the laptop HD, and go!
I beat the piss out of my machines, and have yet to overload the CPUs in this laptop. It's really quite impressive.
Excellent. I hadn’t thought to run XP off an external. That may be just the ticket. Thanks dayglored.