Keep losing network connection, especially after waking from sleep, but...

For a while now, my G5 would have intermittent problems not finding the network after it has been asleep for a bit. I used to resolve this by resetting the router, or sometimes putting the Mac back to sleep and resetting the router.

Lately, I discovered another fix: wake up my MacBook. The MacBook wakes up, connects wirelessly, and sees the network, and shortly thereafter, the G5 sees it too.

I cannot interpret this. Why would it be that the G5 would fail to see the router until after the MacBook is awake (and sees the router)? I never could figure out which component was at fault before, and this further confuses me. I mean, it seems that it has to be the G5, since if another computer can see the net on the same network, it would rule out the router and the cable modem. Right?

So what do I do about the G5, then? Yesterday, it was getting to the point where every time I woke up the G5, it wouldn't find the network (until after I woke up the MacBook).