1. Enable MAC access control on the router. On a D-Link this may entail disabling DHCP and creating a static ARP table.
2. Reduce the LAN size to include only 1 computer, i.e. give it a SNM of 255.255.255.252.
3. Change the SSID to something other than the default and something only you will know.
4. Disable broadcasting of the SSID; If you know what it is then there's no reason to broadcast it.
5. Use some kind of encryption, preferably WPA or WPA-PSK.
6. If your WNIC is 802.11g then configure the router to that as 802.11b is considered an insecure protocol.
7. Disable remote management of the router if you don't need it, and use a complex password for the Admin account.
8. Make sure your box is clean before you do all this, otherwise everything you do will be known to the cracker.
Hug_It wrote:Encrypt your wireless! One, that would answer your question immediately. If you the slow down goes away, problem solved (although I doubt that's the problem).
This is not quite correct. Encrypting wireless doubles the overhead on the network and could therefore theoretically cut the network speed in half.