1. Circular saw: Nothing fancy, but you'll want a carbide blade if you're going to be cutting MDF. You'll need a straight edge, but that's the easy part.
2. Plunge router: You could probably get away with using a Rotozip or similar, but this would be more powerful and not really cost too much more if you shop around. Don't forget the bits.
3. Clamps: You'll want a good assortment. C-clamps are great for holding down the straight edge, while pipe clamps or bar clamps are best for putting the cabinet together. These things are real handy.
4. Square: This is real cheap, but you'll want one.
5. Saw horses: It's so much easier if you've got four of these than just two. With only two, at the end of a cut, something is going to hit the ground.
6. Wood putty: This is great for filling up little spots where the cuts didn't exactly come out perfect.
7. Electric sander: I used mine a lot to help square up edges and clean off excess wood putty and glue.
8. Good ventilation: If you'll be using MDF, this is a must. Cut this stuff outside. The saw dust that stuff creates is unbelievably fine. It gets absolutely everywhere. That being said, you'll also want...
9. Goggles, a mask, and earplugs: Safety first.

After looking at this list (which is not nearly complete) you may want to have someone build it. If you think you may do any of this kind of stuff again, however, a lot of this equipment is a good investment. Look around and price this stuff, and then talk to a cabinet maker. I hope this has helped.

Kevin