[zipperzap]

I have new Power Book 17" - Tiger OS - server with iMac Flatscreen & G4 Tower on the
network. Cable modem. I've noticed twice that the signal strength on my Power Book
has been down to one bar (earlier today). Now at 9PM it's fine. What can be causing
this? Any ideas???

[fulmer]

interference from another RF source.
do you use an older model 2.4GHz cordless phone?
do you have neighbours with wifi stations?

you can use various free utilities to scan for other wifi networks, which would help you determine if there is interference on the same freq on the same channel.