having difficulty setting up this router.

I have a trendnet tew-652brp and none of my other machines(laptop,xbox 360,other desktop)connect, so far only my main desktop works because its connected directly I have been trying for almost 4 hours now with no luck

also my cable modem is a motorola sb4100 surfboard and it worked just fine with my old d-link router.

They are often just plug and play, but the name of the connection will be default unless you've changed it.
My suggestions, follow the instructions for setup and leave security settings off until all devices have connected. Then you can tweak for security.

You'll need to create new wireless connections on your devices also.

You've kind of left yourself wide open as to what problems you have. 'It don't work" doesn't give us much of an idea where your problems are.

I have followed the setup instructions and still nothing both my computers get "limited or no connectivity at all" and how do I create a new wireless connection on my devices?