There is no obvious or completely safe way to do this. Do this very carefully, if at all. You need more business development and legal skills than I have -- that's for sure. There is no easy way to take an idea to a large company, even with patent protection, without risking having them build it instead of buying it. A company with resources can work around patents without violating them.
I don't mean to imply that either Sony or Microsoft are bad in this respect, but in my opinion the patent system is broken. Searching google for microsoft, patent litigation" yields more than 311,000 results. The search for "Sony, patent litigation" yields 118,000 results.
It would take high-powered business development skills to get you the right contacts, and high-powered legal to keep the know-how protected.
Question added to topic Marketing • November 7, 2007
How do I pitch ideas to large companies?
I am a patent owner, entrepreneur and manufacturer with 2 products at major retailers including Walmart. I own the patent for IP on a new product and want to pitch the software and gaming aspects of this product to a major company like Sony or Microsoft. How do I get an audience with them?