I'll toss this out there for the net.knowledgebase:
Finally... a buddy of mine had been struggling with wireless frustrations on a Dell laptop for about 7 months before bringing it to me to look at. I spent 5 hours at his house last weekend struggling like hell to make sense of what was going on. The symptoms were intermittent and rather frustrating. We used 2 different access points, 3 different laptops, one his Dell WinXP, one an HP running winXP and my old iMac with an 802.11b card in it. Only my mac would stay connected consistently. The other two with B/G cards either wouldn't connect at all, could see networks, but not join, could joint but not get ip addresses, or they were able to join and get ip addresses, but surfing was laggy and inconsistent at best.
After a lot of A/B testing of every imaginiable component, updating firmware, updating drivers, trying connections with various computers turned off, I could come to no conclusion other than likely hardware problems on one of the client machines. After getting things narrowed down to his Dell laptop, and seeing wildly variable packet loss in pings to the wireless router on his laptop alone, and verifying that across 3 different access points was the smoking gun that led to me to engage Dell support to go after the hardware problem.
I had to be extremely persistent and allow them remote control of the machine to prove my point, but I did finally convince them to send us a new wireless card based on the packet loss shown in pings to the access point, and watching them get very frustrated trying to use their remote access tool when they had me disconnect the laptop from the wired network. They had me disassemble the hinge cover and remove the keyboard to get to the card to reseat it. It made a slight imprvovement in packet loss but the issue was still very much there. They sent a new module next day air.
The problem module was a DW 1390 WLAN card REV A02. It is a broadcom based wireless card.
The new module came today, popped it in and the difference was immediate and glorious. :-)
Best Regards,