I'm having trouble with game console connection when our imac is being used

This may not be the right thread for this...

When someone uses our imac or any other computer we have, my Wii and 360's wireless internet connection drops a whole lot and it lags in game. It's really frustrating and me and my dad don't know how to solve it. I don't know any internet specs we have or what type of provider we use but does anyone know why this is happening?

Using wireless for gaming is not recommended - trying to use more than one console wirelessly for gaming is most certainly not recommended.

You need to wire the xbox up to the router at the very least. Also it would help knowing the following:

What ISP you are with
What download speed of connection have you signed up to
What is the upload speed also
The statistics from the router
Do you run any P2P software on the iMac?

Without these I am unable to offer further advice.