Drop to DOS using Start > Run and type CMD and click OK
at the C: \> prompt type IPCONFIG

For your wireless adapter you should see 10.0.1.xxx as your IP where xxx is your assigned address.

If not, you should check your IP settings on your Wireless Adapter in Network Connections and make sure DHCP is checked (unless of course you use a static IP setup on your LAN)

If it is something like 169.x.x.x and you ARE using DHCP, then your computer was not assigned an IP by the TimeCapsule router because there was an error somewhere. Might need to check your driver on the PC wireless adapter. Make sure there isn't any updates from the manufacturer (Not the Microsoft Update Manager)

This is under the assumption that the PC's wireless adapter has previously connected to another wireless network before this Time Capsule.