XP SP2 not connecting to wireless

Archived from groups: microsoft.public.windows.networking.wireless (More info?)

I have just bought a laptop with SP2 pre-loaded. I also have an origo
wireless modem/router which is set to 64bit encryption with a shared key not
an open system.
If I try to connect the laptop to my network is says that it can find a
wireless network that is security encoded but will not allow me to enter the
system despite me entering the correct access key. It refuses to obtain a
network address, despite the laptop working (after using WinXPIPfix to
correct the continual problem will windows on its IP configuration - it
always defaults to 169.x.x.x instead of using DHCP to reset the address to
10.x.x.x - This is a microsoft problem that they refuse to fix) when
connected by a cable.
What setting need to be altered to gain access to the wireless network? The
router uses WEP I believe (yes I know it is old and crackable but each of my
machines has its own firewall to stop access between machines on the network
- no files are shared only printers and DVD drives), and it does not have an
upgrade for WPA.