Jools, considering who you work for I'd be demanding a loan laptop!
You are seriously going to struggle to find a dongle for an ancient card like that. We don't really have any lying around anymore either, we're all wireless or use onboard NIC's.
My best suggestion would be to check your options at somewhere like
www.aria.co.uk and buy one off them. Cheap as chips - but use your corporate card!!
And buy me a cool tower case for my PC at home will you, it beeps at me too much
