The cost of Live-ing

Recently, there have been a couple of stories about Xbox Live and the price of downloadable content.
First, on the 1UP Yours podcast from April 6, Mark Rein of Epic Games stated that Microsoft wouldn’t let him release Gears of War maps for free on Xbox Live.
More recently, Major Nelson defended charging $6.25 for three downloadable Guitar Hero II songs. At that price, how much would it cost to purchase all the original Guitar Hero songs off of Xbox Live?
Combine this with the recent announcement of Games for Windows – Live, an effort to bring the Xbox Live network and quality of service (and subscription fee, and downloadable content model) to Windows games.