I found a nifty tool for laptops, called inSSIDer3. Lets you see all wifi channels and all routers in range. That physical location may be close enough for another router to interfere. Also, some B & G units are known to be prone to problems with an N type router on the same channel.
I've got several wireless (WPA-2/AES) computers on a network, and they all work fine except for one desktop (windows 7). When I do a speedtest, it's usually in the 300k down/900k up. When I put a laptop (linux mint 10) or phone next to it (as close as I can get the antennas), and do a speed test on the laptop/phone, I get 11 megs down and 1 meg up. Latency for all is the same at around ~20 ms. I've never had this problem with just one computer before- usually it's the whole network indicating a problem between the router and modem, or with the line further upstream.
No latency issues between the computer and the router- pinging the router gives an average of 3ms response times. What things should I be looking at to diagnose this issue? There's obviously a problem between the router and the computer that's killing the bandwidth to just that machine, but I don't know what it could be. Any ideas?
I've reinstalled the NIC driver with the latest from the manufacturer's website, and I've performed the winsock reset (netsh winsock reset) and TCP/IP reset (netsh int ip reset), but nothing has helped so far. What else should I be checking?