There are several things that can cause this to happen and odds are its not the card upfront. First question is do you have any portable phones? If they operate at a 2.4GHZ range and your using a wireless G router to connect to you will find yourself having signaling issues. If this is the case attempt to move the phone away from it. At least 10 feet including base station.

Also if you are familiar with channeling switch around the channel on your router. Say for example if your running on channel 6 why don't you try to move up to channel 11. This sometimes allows a minor frequency change on the band and you will often find significant performance increase. If 11 turns out not to be perfect also attempt 9 or 1. Do not use 9 or 1 unless 11 doesn't work.

Another problem that can cause this is enviornmental. Do you have anything and I mean anything that would give off a static charge. Washer and dryers on the other side of the wall, fridges, mircowaves, dishwashers, these are all things that have a variety of static levels that can interfere with your signal.

Also make sure you don't have more than one firewall running on your laptop. This can cause a significant problem in your bandwidth performance. Think of it like a airport and taking off your shoes. For every firewall you have imagine it as a checkpoint where you have to take off your shoes. If you have to take your shoes off more than once it can slow things down.

Hope this helps you out a little.

I have D620 w/3945ABG and it doesn't work with my WPNT834 router (best router on market) - it drops after 3 minutes then I get a 169.*.*.* address. The intel 3945ABG is unstable with 'some' access points. I hope they fix this soon! If you find a solution please let me know. I hope you don't experience the same problems.