I personally prefer wired over wireless but sometimes this is not practical. A couple of questions?
1) The computer that is connected straight to the Charter DSL connection, is it wired? Is there more than one plug in connection on the back of the DSL modem? If you have several that is where your other computer will plug in.
2) The 4th computer. Does it have a RJ45
jack on the back of it? The RJ45
jack will look like a telephone jack but there will only be one and it will be slightly bigger the a telephone jack. A lot come with one built in and it is located near the USB ports or the sound card jacks. If you have one this is where you will connect to the DSL box, provided it has addional ports.
If it does not have a [RJ45] jack commonly called a Ethernet Port
you will need to install one. This is very easy.
As long as you secure your wireless connetion you should not have a problem with break ins. Are you having problems with intruders on your other wirelessly connected computers?
The Steganos Anomimoty Suite. I see no reason why it will not work.
Buy all means connect your 4th computer to the DSL. If you do not have a available port on the back of your DSL you may need a hub and a crossover cable to connecct your 4th computer, or it may be cheaper it that case to go wireless. Here is a site I like for network parts.. Just Dealshttp://store.yahoo.com/justdeals/wg311nar.html
I would recommend you stay away from USB if possible.