I am thinking of downgrading from a cable isp to a DSL service. I want to connect both for a few days and switch back and forth to see if it is going to be too painful. DSL is a wireless modem (not sure brand as it is not here yet)and cable modem is connected to a Linksys wrt610n. My main computer has both wired and wireless networking. Any suggestions on the best way to set this up?

You need a dual WAN router. http://www.google.com/search?q=dual...

If this is a private internet connection, simple connect one by cable and one wirelessly. So you can deactivate the normal network card or the wireless, depending on which internet connection you wonna use. Please send a reply, if you solved the problem !!!

I thought about the wired/wireless route but there is another desktop and a couple of laptops that also use this connection (all wirelessly) and I would like them to be able to make comparisons as well.

Basically all users need to switch to another standard gateway. So assuming cable routers internal ip is 192.168.0.1. Also assuming dsl routers internal ip is 192.168.0.2. Then the clients only need to change the gateway and dns settings from 192.168.0.1 to 192.168.0.2, to switch from cable to dsl. If you'd like to manage that, you need another router, where you use the WAN port configured with an internal static ip, e.g. 192.168.0.3 and as gateway the cable or dsl routers internal ip. In this case all clients will use 192.168.0.3 as their standard gateway and you decide, when your users use which internet connection, cable or dsl, by changing the gateway at this router. Please send a reply, if you solved the problem !!!