Slow wireless, fast ethernet

The wireless on my mbp is really slow most of the times -- about 3Mbps. I get 13 Mbps via ethernet. (speedtest.net)
A windows machine connected to the same network gets 13 Mbps on wireless as well as ethernet. Even my iphone gets 12 Mbps.
I guess this rules out problems with the router (DLink DI-524 with WEP).
Tried OpenDNS servers, no change. Also tried disabling file/internet sharing, Ipv6, Little Snitch.

Any pointers are appreciated!

Have you tried upgrading the firmware of the router?

Have you tried doing WPA (if it is enabled on your router) I hear WPA will make it better and more reliable.

I have had the same issue as you but you just have to fiddle with the settings to make it right.

Upgrading the firmware seems to have worked, but I wonder why this only affected the Mac, and not the PC. Thanks anyway!

You also really, really need to change to WPA encryption on the router instead of WEP.
WEP can be broken in a matter of minutes.

Here is a walkthrough.

Done