I had a similar problem when I switched locations, the PC had stuck itself on the default windows allocated IP address, not the one delivered by DHCP.
I am on a win98 machine now so can't look this up but I fixed it by opening a command line window and forcing all IP addresses to be released and renewed.
Can't remember the command but I got it from doing:
IPCONFIG / help
Good luck.
If all else fails try Knoppix! 3.3 seems to work nicely at autoconfiguring wireless nets with PCMCIA cards. At least you would prove it a all works as a system and restore your faith!