I bought the tamron 16-50 2.8. with rebate, just over $400. nice B roll shooting lens. for head and shoulders, its a bit too short. you need to be at like 5-6 feet which is too close. 70mm works nicely, which is where the 70-200 2.8 comes in, its a great talking heads lens. however, DoF is _really_ shallow. well thats the idea you say, right ? well its shallow enough that if they move a bit, you'll have them out of focus which generally doesn't work so hot for your average talking head. you'll want to be at 4 or 5.6 to be safe which may mean upping the ISO a stop. its all a trade off....

I was choosing between the 24-105 and 17-55 myself because they both have IS. Rented both and tested them at a wedding, and fell in love with the extra stop of the 17-55. I really wish the reach was better, but then we'd be paying double for the lens. The IS works amazingly well. I shoot most of my footage handheld with an LCDVF, and it comes out extremely well. So, I'm happy.

The 17-55 f/2.8 IS and the 100mm f/2.8L macro IS make a great combo. Don't miss the 70-200 (or the weight or the price) at all right now.