20-in Intel iMac (early 2006) Tiger -- configuring Airport Extreme Card

Question

Hi -- I come from a mostly "not mac" background and am having difficulty diagnosing a slow internet connection -- and can't tell if I'm trying to use the right tool for the job. (I am using MAC OS X 10.4.11)
My home network uses a Linksys WRT54G wireless router and I've got 3 computers that connect using the router (including the iMac) -- the other two are Windows-based machines. We've got a 2-story house and I've been moving the router and computers around the house a bit trying to come up with the best configuration for a good wireless connection (I'm going to be ordering a supplemental antenna, but don't have it yet).
The two Windows machines (one using a relatively old PCI wireless card) get strong signals. I'm not even sure how strong a signal the iMac gets as I am not sure which utility allows me to see this. I do know that it has a painfully slow connection speed (at least web pages load at a crawl...).
I've got an Airport Extreme Card (0x14E4, 0x89). Firmware: Broadcom BCM43xx 1.0 (4.170.46.9).
I went to Apple's support downloads, and attempted to install firmware updates, but I am getting a message that indicates that these updates are not applicable to my card. I updated the Airport Utility software, but as far as I can tell that utility is looking for an Airport Extreme base that I don't have. Other than that I haven't seen any applicable information using that utility.
I was hoping to reach a configuration area that would allow me to specify 802.11b or g, and allow me to specify the channel -- but other than in the internet sharing section I don't see a place that allows me to do this. (I've currently got our home network on a 802.11g network on channel 8.) We're using WPA personal encryption -- which does appear to be recognized by the Airport Extreme card.
Am I missing something? I've got 3 "Airport" utilities but none of them seem to allow me to specifically configure the internal card. I've gone to "network" under System Preferences, and although I can see a "configure" button when I click on "Airport," it's pretty basic and doesn't allow me to set the channel or anything other than encryption & a password.
I would appreciate any help you can give me. Is this card so outdated that I should invest in a newer one? Am I limited by my outdated OS? (I hesistate to upgrade OS's when things are working -- in the Windows environment at least newer isn't always better...) Thanks. mcaren

Answer 1

Thank you Duane for your response.
I have only noticed a huge difference in the connection speeds of my iMac and our other computers in the last 6 mos. to a year. I did notice an improvement in speed when using a Rosewill USB wireless adapter -- I had a good wireless signal but would intermittently lose connectivity (and their user support was basically nil...).
I can't tell if I'm actually seeing an improvement in our other machines' connection (perhaps from the tweaking I'm able to do) or if in fact the iMac is slowing significantly. I think it's the latter. I've actually swapped out machines in the same position to see if location is at fault -- and I get no improvement in connection speed. I've had the iMac connected with ethernet to our router when possible because it has had such a slow wireless connection, but I needed to move the router recently and would like the iMac to stay in another room.
I've also read a lot about connection speed issues with Airport, but these reports are usually blamed on Leopard updates (there might be similar Tiger issues, but I don't read about them...).
Oh well. I'm hoping someone out there has some tricks up their sleeve as to how I can improve my wireless connection speed. Thanks for the help! mcaren