How do I use 2 internet connections at the same time?

[wild_legs76]

I currently have wireless router set up with a DSL connection and my laptop is wirelessly connected to it. My roomate has a cable connection and he has a wired router. Would it be possible to connect my laptop wirelessly to my router and connected to his with a wire and specify which internet connection to use when downloading a file? How would I go about doing that?

P.S. Free methods are preferred. I am not going to go buy a twin-WAN router.

Thanks.
Take this scenario for example: I want to be downloading a file using one internet connection and browsing the internet using the other.

I don't want them to be shared.

Thanks for the suggestions.