If you use wireless networks, it's strongly recommended to test your connection with some ping test tools.
There are many ping tools in the internet, just download one and do a ping test.
(I use the Ping Tester http://www.pingtester.net/ trial version to test my connection)
You don't need to ping an internet address, you can just ping your router IP.(like 192.168.11.1)
Keep pinging for 2~3 minutes, the reply time should be very stable, like <10 ms.
if you see some timeout or >1000 ms every 60 or 70 seconds when pinging,
your connection was influenced by the MS wireless connection auto-check bug.
The bug can be solved by many methods, depends on your OS and wireless network hardware.
Just Google "wireless spike every 60 seconds" , and you will find many answers for it.
In my case, I need to uninstall my Vista wireless card driver, re-install the XP version driver(use compatibility mode),
and run the Vista Anti-Lag software to make the connection spike disappear.
Hope it is helpful...