I have a two year old asus netbook eeepc which, for some reason, has difficulty connecting to some routers. I dont' know if my driver needs updating, or if its some setting in the router, but on occasion, when visiting friends I have been unable to obtain an IP from the router. The netbook sees the router and has a signal but can't connect.

Any suggestions?

See if your netbook is set to obtain configuration data from the router or if there are values already plugged in like 192.168.1.1 or something. If it isn't set to obtain config data from the router then UPnP won't be able to assign it an address and it could end up with the same address as someone else on the network or just not get access. This would probably be the case if you've set up the netbook to use port forwarding (for torrents) which requires a static IP.

That's probably the issue.

Yes, that sounds like it could be it, cheers!