With wireless password off, even a b wireless card should connect to a Gen5 AE.
Ok, so I turned off all security, and tried the 3 channels noted above on the 2.4Ghz frequency... And no go on any of them. As there is no password, I'm not entirely sure what the error was, but it would think about it each time I tried to connect.... then nothing.
I would still expect it to throw up a message of some sort. Not to just stop.
There is a couple of things cosmichobo you can do..
1. Force the AE off N wireless.
I am deliberately using a 5.6 version utility. Set radio mode to b/g. The default setup should still work with b wireless but it can help things along to give it a bit of help.

2. Go to the advanced.. put the logging level up to debug.

Then check the log.. by toggling the wireless on the computer I get associated and disassociated connections showing up.. what I don't know is if AE log will show attempts at connections.. Cannot remember. Some other brand routers do a better job of showing attempts at connection.

If you are trying to make an antique computer work.. you can buy old airport cards on ebay readily enough.. pick one that is G wireless..
Make sure the antenna is plugged in correctly.
If you just want network connection but without too many cords.. you can use an airport router in extend wireless mode and plug that in as a wireless bridge.