small business networking issue

Hi Guys,
I am at the end of my rope here with a small business network.
I have two imacs and a macbook. The two imacs are running 10.5 and the macbook 10.6. I also have a fuji xerox DocuPrint C1190FS mutlifunction laser networked. This is all networked by a linksys WAG160N. I have shared folders on one imac that the other two machines access (containing normal files and also MYOB data) When the whole system is booted up, everything works perfectly, however, over the course of 1-3 hours, each machine, and the printer, drops off the network (by this I mean they stop being to see each other, however internet connectivity never drops off). Rebooting the router occasionally works, at other times just waiting a day or two will bring the other machines back to the view of each other. I have tried everything in my head including:
Repairing permissions
Changing channels
Changing encryption
Reviewing all sharing preferences to make sure they are ok
Physically moving the router
Refreshing the firmware of the linksys and the printer.
Using another router (same model)

Any help would be much much appreciated as I am rapidly going bald trying to figure this out

Cheers
Toby

This points to an issue with the hardware dropping the mounted drives when entering into 'sleep' mode...will need to dig out the settings, as i can't remember off the top of my head...

Recall reading some time ago that when i comes to Apple and Wireless it is better to use Apple for the wireless network. It is not that others brands cannot be used successfully, it is just that if u don't have the time/knowledge to tinker and get it set correctly then go for Apple and it plays more nicely with less set up. My network has been going 4 years now and it still can sort VoIP SIP where as the router on its own will not, but both Extreme and Time Capsule seem to be able to figure it out.

Yeah, agree with you Collin - haven't had any issues with drives dis-mounting etc, since disabling the wireless SSID on the wireless router and using the router (as DHCP only)<connected to>TC (Wireless SSID enabled/bridge mode off)<connected to>AEX (extending network) setup for all hardware (mixed windows/macs)...