If it works OK connected "wired" to the same network, then that narrows down the problem a bit.
Does the wireless device on your computer "see" the network you're trying to connect to? Can you then "Connect" to it? Is it WEP, or WPA, or what security, and is it asking you for the code?
If you aren't getting as far as connecting to the wireless bit,then you will get that "Windows default" 169.xxx.xxx.xxx IP address - which will do nothing for you.
If your wireless connection reports that you are connected to the server, what else does it tell you? The "Properties" ought to tell you something - even if not an IP address.
What information do you get at that stage?
I'd say step 1 is to be sure you are connected to the network. Once that's done, the rest should be easy. From my experience, getting the wireless bits to "see" and accept each other is the tricky bit.