Hi Shawn,
Here is a clip from Ben's (from Cisco) excellent post (he knows ALOT more about this than I ever will :)
The HWIC-AP is supported with the 1841, but you must be running a 12.4T IOS image (in addition to the correct feature set). I'd suggest 12.4(11)T with Adv. Security or Adv. IP Services Feature Set. Make sure you meet the minimum memory requirements as well.
Your next best option would be 12.4(9)T2 with either Adv. Security or Adv. IP Services Feature Set."
Hope this helps! This should definitely work.
Rob