Experiencing very slow browsing at times (atheros wireless)

[Petr Janda]

Petr Janda wrote:
Matthew Dillon wrote:
:Just a few moments ago another slowness was happening so i ran the 2 
:tcpdump commands. After about 1-2 minutes it came back to normal 
speed :so i tcpdump.
:
:You/whoever wants can get the dumps here:
:
:http://www.punchyouremployer.com/files/tcpdump.tgz
:
:Please have a look and tell me if you can see something wrong.
:
:Petr

    It looks like you have a ton of packet loss somewhere.  What
    machine was the tcpdump run on?    
It was run on the client. 192.168.1.50 is my DF workstation which i 
ran tcpdump on. 192.168.1.40 is my server (punchyouremployer.com). 
192.168.1.1 is my default gateway, 220.233.111.100 is my public IP. 
There is DMZ configured on the router pointing to 192.168.1.40

Petr

Another tcpdump is available:

http://www.punchyouremployer.com/files/tcpdump2.tgz

This time I also ran ping during the slowness. I also suspect its radio. 
I replaced router, i replaced card. nothing seems to help. :(

How do I set speed and preamble? Do i do it on the router?
Petr