So I'm half way to being all Mac in my house. I have one Windows7 notebook left. I currently use a Trendnet N router, which is pretty reliable. What would be the compelling reason to use an AirPort Extreme Base Station?
If you are having problems with your current set up I would recommend it. If you aren't, i wouldn't bother. I like the ease of use and being able to use the Airport App to control all the settings right on my phone.