FYI, I use a MacBook Pro with Firewire 800 1TB and 1.5 TB G-Raids and I’ve cut a feature length project in 1080 24p with 900GB worth of source clips. No problem unless you’re piling on the effects and video streams. 720 projects are no sweat at all.
A 2nd Firewire bus (less than a hundred bucks) in the express slot allows for 2 G-Raids at once, or a G-Raid plus a Firewire camera-to-monitor. I also monitor sometimes with a 23″ Cinema Display, especially when more than one person needs to watch something for review.
eSata would be great and a Matrox is the solution for monitoring seriously from the MacBook. But in the meantime, you can make do with Firewire and save your pennies for a Mac Pro and whatever magic hardware will be available when you’re ready.