Losing network connection

As of late, I've been losing my internet connection in my home after I've been on the system for about an hour. As background, I have a wired Motorola cable modem with a wired Linksys router (I use Comcast as my ISP), and I also have a wireless router (Netgear Super g) in one room of my house. This problem started a few months ago, and it seemed like I always had to reset my modem to regain connectivity. My cable modem was about 6 years old and I thought that might be the problem, so I bought a Motorola (Surfboard?) modem and things seemed to be much better. However, the problem still comes and goes. The Netgear router is about 3 years old. I should mention that there are several users in the home and everyone uses wireless access. I don't know a great deal about this, but I'm beginning to suspect that both routers are trying to kick out IP addresses that are conflicting with one another. Tonight I was using the wireless access and lost connectivity after 53 minutes. I waited about 3 or 4 minutes and then tried to reconnect and things seemed fine. I did not reset the modem. The issue seems to be more of a problem for the PCs in the house than the Macs, but that's mostly anecdotal data. If anyone has any ideas, I'd love to hear them. Should I replace the wireless modem with just an access point? Any help would be appreciated.

Let me confirm that ALL computers on the network are having the same problem? What are the different operating systems? Both XP and Vista have diagnose and repair options. In Vista it is control panel, network and sharing center, diagnose and repair. I forgot exactly where it is in XP but it should be under network connections under the properties for the device. Also on each computer from control panel enter internet options, then connections, and then LAN settings. Make sure that Automatically detect settings is checked. The others should probably be unchecked. Now you need to go into the router settings and make sure it is set as a DHCP server and to automatically assign ip addresses [see your user manual]. You might also try resetting your router to the manufacturer default settings [again see manual and contact your ISP to see how the router must be configured to connect to the modem (ie automatic/manual ip address, user name and password)]. If you had password protection enabled previously it will have to be re-enabled.

I know it's an inconvenience but I also I recommend disconnecting the router and connecting only 1 computer to the modem. You will probably have to unplug the modem's power for a few minutes. After correctly configuring the computer [contact your ISP to find out how the computer must be configured] and bypassing the router if you are still having problems with your computer losing the IP address then the problem is most likely with your ISP especially if you try this with 2 or more computers connected (1 at a time) directly to the modem [you'll probably have to unplug the modem for a few minutes in between switching out the computers]. In that case I would contact your ISP. If a computer doesn't disconnect when it has bypassed the router and you have reverted to the default settings on the router then I would suspect that the router is going bad.