Pinging and wifi scanning - why do these adapters differ in behavior?

I'm curious to find some insight on a wifi issue im having. I have a WUSB600N and have been having issues with it. Basically, windows would scan for networks at times and cause any video i'm streaming to stutter for a second and then catch up. I've noticed that when I'm doing ping 192.168.1.1 -t and manually scan for networks, it spikes to 3000+ ms or times out.

Normal I think, I just have to try vista anti-lag or something like that to get it to not scan. However, on my XP laptop, if I do the same command and manually scan for a network, I don't get any timeouts. Also, if I do get a timeout, it doesn't wait 3 or 4 seconds to complete, it simply chugs along as if nothing happened.

I believe this behavior is why my one machine is sputtering. It seems like Windows will scan in the background for networks, but, depending on the wifi card i guess, it can either pause the connection for a few seconds or keep on going.

Can anyone explain this behavior and why it would be? Thanks.

Ryan

I limited my profiles to only one - mine. There are no other 5ghz AP's in the area.

The only thing is, my signal strength sometimes goes low. Is there some threshold for when Vista automatically rescans networks or renegotiates speeds when the signal strength gets too low?