hmm...SSID is basically the "name" you give your connection. It probably isn't an issue for your regular desktop computer because Windows XP automatically scans for available SSIDs (wireless router signals) and you simply connect to it. If you look at the wireless connection in your desktop computer and see what that connection is named (like "pixelpnet" or "myrouter" or "jsmith436"), that is the SSID for that signal.
another possiblility is that your wireless card settings are set on "Wireless Network" instead of "Access Point", you want "access point" if you are simply using your wireless router for the internet.
I wish I could be more specific in my instructions, but I have no idea how to access your laptop wireless card settings. Try to see if you can find the settings for SSID and a drop down menu (or check box) that changes from "Wireless Network" to "Access Point".