My personal opinion is that you could constrain your ability to do work quaickly and efficiently, but that all depends on the video you intend to edit. Notice that I said what you intend to EDIT, not deliver.
If you're simply shooting DV -- and DV ONLY -- it ought to be okay.
However, if there is any chance at all that you'll do HD, or even SD video with a higher bitrate than DV, you're going to need something beefier, and that's no lie; a single drive wouldn't be able to sustain the kind of bitrate you'd need.
I include HDV in this category, too. Why? Because unless you intend to do cuts-only editing with no effects, your machine will be woefully slow. Even though the picture may be bigger, the HDV codec is even worse quality than the DV codec. You'd want to capture HDV video in a codec that maintains quality better than HDV for any kind of effects work... and when you do that, the bitrate shoots up, and your drive would be inadequate.
Unless you're absolutely certain that you will never, ever be supplied video from a source other than your own, or buy third-party video to use in your projects, you would spend a bunch of time rendering... and what fun is that?
This topic has come up frequently on the Final Cut Pro Forum. If you do a search in that forum using a search term like "Macbook Pro", you will find many threads similar to your situation.