[Hampshire] [OT] Dell Inspiron Wifi Card Blues

I was wonder if anyone can help with a spot of bother we have
encountered regarding the Dell 1370 wireless 802.11b/g card that resides
in my wife's i1300, which is running WinXP.

Basically, there are certain areas within certain sites (Amazon, Tesco,
egg, all usually once she has logged in) that grind to halt rendering
her browser (tried Firefox, Explorer and Opera) unusable on those sites.
She is going out via the same router used by several other wireless
WinXP machines that don't appear to be similarly affected, and when we
connect the laptop via an ethernet cable the problem disappears.

I have tried updating the drivers to the latest release, I have tried
uninstalling and reinstalling, and I have even tried moving from WinXP
Home to Prof, as this was previously the only 'Home' machine on the network.

None of this made the slightest bit of difference so I went out and
bought a pcmcia wifi card, only to find that the slot on the lappy is an
Expresscard one... doh!

Anyone got any thoughts on where I might go next? I don't really want a
USB card as I don't like dangly wires or protrusions, and there don't
seem to be any Expresscard wifi cards available yet. I could always
replace the existing internal card, but I am a little wary of throwing
good money after bad. I appreciate that cuts down the options somewhat,
but it'd be nice to have a better understanding fo the problem if anyone
can assist.

Cheers,

Sean