Help with slow DSL

Hello.
I have 2 computers running off a Linksys wireless router. One is connected through ethernet and the other wirelessly.

I can browse very quickly on the wired one. The wireless one, however, is very slow. Windows wireless shows an excellent connection at 54mbps.
But the connection is extremely slow.
Through cmd.exe, I pinged my router at 192.168.1.1, and at times I get up to 75% packet loss out of 4. The best is 25% packet loss.

So the problem must be with the wireless, but it's very strange that I show a strong connection.