As Marco pointed out, you need to use the
same parameter values on both ends of the wireless link (access point at gateway and wireless NIC adapter on Vista PC); e.g. "System Set Identifier" (SSID), "Encryption Method" (None/Off, WEP, WPA, WPA2), Encryption Key Value(s).
The Vista machine also needs valid TCP/IP configuration values for your network. This would include "IP Address", "Subnet Mask", "Gateway Address", "DNS Address(es)". These can be set manually within Vista or automatically using the DHCP server built into your wireless gateway (if Vista wireless adapter connection is configured for automatic assignment).
It would be best to disable all security on the wireless link until you successfully connect, then add security one piece at a time until you achieve the security level you wish. Specifically start with your wireless encryption set to "None" or disabled on both the access point and the wireless NIC on your Vista machine. I would also start with the Vista firewall off or disabled. At any rate
you should not be using WEP (either 64-bit or 128-bit). It is weak security. You should be using the strongest security (encryption method) that all of your wireless equipment supports. This would be either WPA or WPA2. See the "Wireless Network Security" link below for tips on securing the wireless network.
The
User Manual for your wireless gateway is well written. You should pay particular attention to:
Page 42 - LAN IP Address
Page 42 - DHCP Server
Page 54 thru 58 - Wireless Settings
Page 58 - Wireless MAC Authentication
Page 59 - Wireless Advanced Settings
Page 81 - Troubleshooting
Generic References. Pay particular attention to the links for the wireless adapter configuration in Vista along with its sublinks (indented).
What is Wireless Network Wireless Router Configuration Wireless Adapter Configuration in Vista Quick Way to Check Network or Wireless Adapter Driver Status in Windows Vista Configuring IP Address and Other Network Information in Windows Vista WLAN AutoConfig Service in Windows Vista Using Windows Vista to Connect Wireless Network Wireless Network Security