Make wireless rounter wired

Hello Everyone,

I am looking to buy a router.
One that I can hook up to my dsl modem.
I would like to connect more than one computer at a time.

I have DSL with ATT (formerly sbcglobal).
My dsl modem is a Siemens speedstream 4100.

I am looking for a router with NAT translation and SPI (statefull packet inspection)
For security.

I have looked at all of the routers and reviews on Amazon
And new egg and here at DSL Reports.

It seems that one that is the most reliable is the:
Linksys: Wireless-G Broadband Router WRT54GL.

But is doesn’t seem to have NAT transatlation, at least according
To the Linksys web site, it only has SPI.

And it is wireless. I have heard that I can shut off the
Wireless part and use it as a wired router.
Is this true? I want it to be secure.

I will be hooking up other peoples computers
To it so that I can diagnose and repair them
Most do not have wireless capability anyway.

Thank you in Advance

Laurence

What I mean by repair, is to fix or upgrade there software.
Usually applying patches, getting rid of spyware, reinstalling
Windows if necessary, installing Firefox and checking there
Security settings, etc..

The only hardware I have experience with is client side (pc based)
I am just learning the networking part of it.