Wireless Connection issues, SP1

I just had to format my drive/set up a new boot disc, and setting up internet is a major pain. I'm using a linksys wireless-G adapter to connect to a home network on another computer (this one) - I install the drivers, and create a connection..

Windows has a popup saying wireless networks are available at the bottom right of the desktop, so I open that and try to connect, but at the same time it says "Wireless Connection Unavailable" on network connections beside the network I created and has a red X on the right side of the icon. The wireless connection's icon also as a black Y shape symbol on it which I've never seen.
I didn't have this issue with SP2, so appears to have something to do with that - I'm using an original disc, which I think is SP1.

When I attempt to connect to a network (typing out a password like 40 characters long, twice) it just closes the wireless network window and does nothing.