It is possible to set up a wirless network top work in ome of two modes.
Adhoc, as it aame suggest is just network of two wirless computers talking tot each other
Infrastructure, which is where access is made using access points.
Check that both PCs are working in Adhoc mode.
Check that you have duplicate setting for SSID etc.
When setting up it's a good idea to leave you SSID (you network name) being broadcast or beaconing. However, once up and running you should turn your SSID beacon off.