Rob,
I'm on my way out but I'll give you some info on Jerome's questions and he can elaborate later.
One way to determine network settings:
Click Start > Settings > Network & Dialup Connections > and choose a "Local Area Connection". If you have more than one on there, do them one at a time. Click on Properties and make sure you see "Internet Protocol TCP/IP", then click on it and choose properties. That will show you your settings. The big question is, is that WL310 acting as a DHCP server. If so, make sure your TCP/IP settings are to "obtain an IP address automatically".
It might help to know the IP addresses of the two systems. They could be picking up separate network addresses (if the AP isn't a DHCP server. To get the IP:
Start > Run > type in "cmd" and press enter > type in "ipconfig" and press enter. This will list your IP information.
The SSID is a unique identifier for your wireless network. If you don't know what it is then you likely haven't changed the defaults and shouldn't be having an issue along those lines. Especially if both systems are talking to the Net individually.
What did you mean about your "not simultaneously" comment??
Do you run any firewall software? That could keep the systems from seeing eachother, or connecting anyway.
Jim