Multiple systems on one network is a pain...

I seem to always have problems with internet connections and my mac.
I'll be the first one to say i have very little knowledge of networking, and setting up routers, but i do know enough to get them to just work. Which i feel might be my problem.

I currently have a D-Link DIR 615 router hooked up to my iMac (wired), and the same connection is wirelessly connected to a laptop running windows, as well as a PS3, primarily used for netflix. I don't do a lot of online gaming.

I often go through some very sluggish periods, either on the imac or while watching netflix (nothing more frustrating than having that "Retrieving..." screen pop up every few minutes. The only way i have found to fix this is simply resetting the router. Is there any way i can configure my systems to get a more consistent connection? Any advice would be appreciated,
Thanks!
-Adam.