Yes I have the same computer and same problem. I went back to the apple store today and sat outside and played for a couple hours and never dropped once on their connection. I bought a new apple router airport extreme we will see how that works. I have read quite a few reports of the same issue seems they don,t get along good with some routers. Just for info I have a 2wire router that seems to randomly drop off every 20 or 30 mins.
Phil