Will work just fine,...

The only problem i can see is if you wanna play too many layers, than your videos will slow down. I have a MacBook (non pro), and I had a situation with one G5 with problems, and I used my MacBook and save me the day.
Dual Head or Triple Head to go will work on macbook without a problem, just do not know how the Graphic Board wiull handle, since is a 256Mb I belive will go OK, may be some one has the experience on that.
If you have a Macbook Pro with a Firewire 800, you definitly wanna use a external Hard Drive for CONTENT, like the LaCie (already 2 RAID internaly) Big Disks or so,...