I've read David's answers. Where do I find SNR, anyway?
We used one WRT54G for a year. Router two floors, maybe 25', up from Winbook laptop.( Cable internet) Drove us nuts. Dropped often at various times. Signal strength would show Good, but no connection. Calls to linksys, newgroup queries, searches for help..no improvement. My lady finally tired of me trying to prove myself and called a geek.
We now, out of pocket again, have a Belkin Pre-N router, which pretty much does the job. Occasionally won't connect, but does after couple of minutes.
I wouldn't ask you to trash seven routers, but if you'd like to buy another WRT54G, I have one.
And I looked at sveasoft and other non-linksys upgrades, but didn't want to screw up whatever linksys warrenty we had.
Your client card software may report it. Point being that simply having a report of signal strength is somewhat meaningless if there's noise (inteference) of the same proportion. Ideally there shouldn't be but if I fire up a video sender for example or a wireless camera, I can kill the signal from my router without any effort at all.
If you disable the windows zero config thing and use the software that came with the card, it will likely have better diagnostics and reporting. The windows 5 bar icon is somewhat "off" from what the manufacturers diags tend to report.