Macbook: 13" 1st Generation
Operating System: OS X 10.6.3
ISP: Time Warner's RoadRunner
Modem: Motorola SB5101
Router: Linksys WRT54GL
Firmware: Tomato 1.27

Here's the situation:
In our house, we have three Mac users. Two of them have 1st generation macbooks and I have the 1st generation of unibody macbook pros. Of the three of us, I am the only one that has no trouble connecting to the internet. The other two are able to connect to our network just fine, but are unable to connect to the internet. While looking at Network Diagnostics, the Airport, Airport Settings and Network Settings bubbles all remain a solid green, while the ISP, Internet, and Server bubbles all alternate between green and red (they do not flash, it's more of a one-minute-it-works and the-next-it-doesn't situation).

I did some research via googling the problem and found that some options may be to reset safari (clearing caches sometimes seems to help?), reinstalling the operating system, or... Some other things that I thought probably wouldn't help much. However, after resetting Safari, my room mate saw a significant improvement in the amount of time he was connected to the internet -- however, it's still very spotty.

The strangest bit out of all of this is that both of my room mates can connect to other wireless networks/internet better than they can our own at home. For example, they sometimes resort to leeching internet off of our neighbours because it's more consistent than using our own.

My room mate noted that his connection seemed to get all dodgy after he installed the latest update from Mac, though he didn't say which program it was for or if it was an update to the OS. I haven't updated it myself just yet, and probably won't for a while now (in fear of the same thing happening to my computer!).

If you have any suggestions, I'd be happy to hear them.