I had the same problem with my D-Link wireless G setup (Turbo G @ 108 mbps). I opted for a new router from them and got some seriouse boosted performance. The router isn't a “home” router but a business router with QOS support. My connection throughout boosted almost 50% at my farthest area.
Here is a link just in case.
http://www.dlink.com/products/?sec=0&pid=493
