Over the weekend I did a clean install of Tiger on a second internal drive. Ran software update and upgraded to 10.4.1. Everything is running very well so far.
When I was downloading the update for 10.4.1, I noticed that it was taking a bit longer than normal, and my airport signal strength meter was all the way to the single dot at the bottom. I juggled the "T" antenna and checked the base station, but nothing helped. Still a very low signal- lower by far than I have ever seen. Later in the day, I re-booted from my drive with 10.3.8, and the signal went back to full strength. Seemed odd to me, so I immediately re-booted 10.4.1 again, and sure enough, the signal went way down, and even dropped off completely at one point. When I re-booted in 10.3.8, and the signal went back to full strength. Nothing changed from one reboot to another, just Panther to Tiger and back again.
I haven't run any diagnostic tests to determine exactly how much the signal is dropping, but it is very noticable. I've never had signal problems before, and I do not have any nearby neighbors. I'm running a Dual 2Ghz G5 with Airport Extreme card and base station.
I don't have Tiger, but supposedly, the indicator no longer shows signal strength, but rather, signal throughput (i.e. 5Mbps vs. 10Mbps). Kind of a weird change to make... but I would time the speed of the downloads to see if it is a real decrease in "speed" or just perception.
I checked the speed this evening- you are correct. there is no change- the meter is just showing bandwidth instead of signal strength. There is no indication anywhere that this is the case. What a goofy thing to change- I wonder what was the logic behind THAT?