timmcat,
Assuming that the problem is not wireless-related, but IP related:
How are you assigning IP addresses? all fixed? DHCP from the WAP?
Can you supply the IP configuration details (IPCONFIG /ALL) - IP address, subnet mask and default gateway for the new PC and your gateway PC?
On the new PC, what happens when you ping localhost? 127.0.0.1? Its own IP address? Its own name? Can you ping any other PC on the network? Can you ping any other name?
SD