Is your wireless connection detecting the SSID? If yes check the IP address available or not? If yes try to ping the default gateway.If not try to configure manually(possible dhcp client request not running or block by pc firewall).
If your wireless connection not detecting the SSID, check the router setup, SSID broadcast should be ENABLED. If enable try disabling wireless security(Windows vista has some issue with wireless secuirty).
Try to reset the router to factory default and reconfigure it.