D-Link router connection timout w/ macs?

I have a d-link WBR-2310 router. I have a brand new motorola cable modem. The problem is that my connection seems to time out every 10-15 min. The signal strength never goes away or fluctuates, the connectivity just disappears. It either returns by itself within a minute or two, or it returns almost immediately if you turn airport off and back on again. This happens EVERY 10-15 minutes w/ my macbook and both of my roommates' G4 iBooks. i just had the internet company confirm that all of their equipment and service is working properly. i've been on the phone w/ dlink multiple times to solve this, and they've had me change a ton of settings within the router, but nothing seems to be working.
The last tech i talked to at dlink said that they've done all the troubleshooting they can with me and for me to contact apple about possibly changing a hardware setting in my networks prefs. She also said that this problem has been semi-common with this router and macs. I am asking here because i don't have applecare, so i can't call. and the nearest mac store is 40 min away. this is the only network this has ever happened on. and like i said, it happens to all of the computers (all are apple) in the house.
The connection is great when it's on, it's just lame when you're chatting or downloading a large file, and then the connection randomly drops on that regular of a basis.
Oh, and it mainly seems to happen when there is more than one computer surfing.
what to do??