Very slow network - Ubuntu

["A. Ben Hmeda" <abh@canada.com>]

I have searched ubuntu forums to no avail. My network connection has
slowed down considerably since I installed Ubuntu Dapper (6.06.1 LTS) I
have disabled ipv6 in /etc/aliases and Firefox, still slow by about 50%.

My machine AMDSMP is dual boot w2k/ubuntu 6.06.1 LTS (2xAthlon 2000+ 512
RAM), network is at full speed with win2k and Fedora Core 5 (now
deleted) on this machine.

I have another Ubuntu 6.06.1 LTS machine SERVER (2xP3-500 256RAM) and a
Win2k KIDPC (P3-866 512RAM) on the same home network that do not have
this problem with the network slowdowns.

My benchmark is http://www.testmy.net/ website. Every machine on the
network has been tested separately, while other machines were turned off.

Didn't matter whether the connection was static or dhcp.
I have also noticed slowdowns (high latency) while playing on-line games
like bzflag
My /etc/network/interfaces :
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.1.2
netmask 255.255.255.0
gateway 192.168.1.1

ifconfig output:

eth0      Link encap:Ethernet  HWaddr 00:04:5A:9A:8C:6E
          inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:46508 errors:0 dropped:0 overruns:0 frame:0
          TX packets:31020 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:43829777 (41.7 MiB)  TX bytes:4368831 (4.1 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:472 (472.0 b)  TX bytes:472 (472.0 b)

What went wrong?