If you have a little extra cash, you might want to think about getting a set of HIDs. I got mine from SharpHID.com and they're significantly brighter than my stock halogen bulbs were.
I got the Apexcone 35W H7 5000K HID Kit for $150 (comes with a lifetime warranty) and I got the battery harness a week or two later for $35 since I had problems with one of the lights turning on (a common problem with the 2007 WRX, but you probably won't have to worry about that since yours is an 04). The light output is amazing and the color of the bulbs is almost completely white with the slightest hint of blue. I think they're perfect, but that's my opinion. The kit was completely plug and play, no cutting wires, and very self-explanatory. The only thing I had to do was cut 1.5" (I think) holes in the back of the plastic caps that screw on behind the headlights to provide a water-tight seal for the bulbs. Just some food for thought.