[Hampshire] [OT] Curious Network Issue

First up, this is OT to the point of being a WinXP Prof related issue,
so read no further if that causes offence!

Now, I have an odd problem with regard to my wife's Inspiron 1300's
mini-pci wifi card. Essentially it grinds to a halt on certain sites,
namely egg, Amazon and Tesco. From what I can gather this usually occurs
after she has authenticated and especially when she is trying to pay for
an item.

She has tried various browsers (Explorer 6, Firefox 2 and Opera 9) and
the problem persists. She has tried other PCs in the house, some of them
connected via other wireless cards, some via ethernet, and the problem
disappears. She has tried hooking up her laptop to an ethernet cable and
the problem is not in evidence.

XP is patched up to the minute and I have upgraded to the latest drivers
for this card and the motherboard, which made no difference to the problem.

The only consistent thing in all of this (where the problem is in
evidence) would appear to be the card and the connection to the
motherboard and beyond. I cannot think of any reason why the hardware
would be at the heart of the problem, but I am stumped.

I cannot buy a pcmcia card as the i1300 only has an expresscard slot
(there aren't, as far as I can ascertain, expresscard wifi cards on the
market yet). I don't particularly want a usb card due to the possibility
of damage to the usb slot when it is moved around the house. I am
dubious about buying a replacement in case I am throwing good money
after bad.

Anyone got on any thoughts on this?

Cheers,

Sean