I had luck with the 5100 on an HP laptop and the wrt310n linksys router by chaning the following settings... in the hardware properties of your wireless card change the 2.4ghz to auto then change this on the router:
as seen above the intel cards have a problem with TKIP encryption so after I changed it to AES I now have a connection at 135mbps.
hope this helps although a little late....
I have the same problem. I have tried everything suggested above but it still didn't improve the connection speed. The driver is up to date according to Dell's system diagnosis. Please help! I have the following hardware:
INtel wireless 5100 AGN card
Dlink DIR-655 router.
I plugged in my Mac and it's connecting at wireless N (~144MBps) but the Dell is only connecting at wireless G (54Mbps).
after spending all day trying just about every setting manually on my wrt160nv2 i gave up , i managed to get 65-135mbps with a very good/excellent signal.
so i set my wireless settings to manual / network mode mixed. radio band auto wide channel auto standard channel auto ssid broadcast. now its getting 130-150mbps
be warned i found that when the signal drops to good it means nothing the speed tapers off dramatically to around 6-15mbps worse than the old 1394g card