If you're contacting on enlarging paper, a higher wattage bulb will give you exposure times too short to control easily.

If you're contacting on Lodima silver chloride paper (or the discontinued Azo, if you can find some), which is much slower than enlarging papers, you'll need a higher wattage bulb, preferably one with more UV output.

The setup you're proposing is pretty much what I used for contact printing two apartments ago. See the first photo in this post--

http://www.apug.org/forums/forum43/1...html#post93420

The lamp I use is a simple Ikea halogen desk lamp with the UV filter removed for contact printing on Azo or Lodima.