This step assumes Windows 2003/2008 is your DHCP server for your Wireless network. Raising the wireless gateway metric to a value greater than your LAN metric will force traffic to use the lower metric.
a) Right click Scope Options on your wireless scope and choose “Configure Options”.
b) Click “Advanced” tab.
c) For Vendor Class, choose “Microsoft Windows 2000 Options”
d) Put a check in “003 Microsoft Default Router Metric Base”
e) Set a value fit for your situation. I use 0x1f4 which gives it a metric of 525, which is higher than all other network metrics we use.
You can repeat the above steps for all your WIRED scopes, giving them a value of 0 for the metric. This is the BASE VALUE of 10. This is only needed IF your base value is greater than 10 (you can see the value by running “route print” from the command line).
For more information, see http://technet.microsoft.com/en-us/library/cc782411%28WS.10%29.aspx, do a search on page for “default router metric base”.