My experience is a bit limited, but it sounds like you want to stream the programming from your cable card device to your three TVs. WMC (Windows Media Center) is the only program that can access the protected content from the cable card device. That's the bad news. The good news is a bit more convoluted.
Protected content can be broken into two groups, Copy Once content and everything else. Copy once content can be played on only the pc that records it (and on the "extenders" connected to that pc). All other content can be shared freely between your networked conputers. Since my cable provider only marks the HBO/SHOWTIME/etc., content as copy once, I can share most of the content that I watch accross my network without restriction. Others in this forum are not so lucky as they find that their cable provider marks most content as Copy Once.
As more cable providers move to marking more and more content as Copy Once, the only viable otpion (other than something illegal) is to use a WMC pc as a "server" providing content to extenders located at any TV that wants to view the protected content. Currently, the only options are the XBOX (which requires a subscription), some out of production extenters that can be found on ebay and the like, and the soon to be released Ceton Echo devices (much anticipated around here). The price for the Ceton devices is about the same as an XBOX, but no subscription is required. The full capabilities of these devices is still a subject of speculation regarding what video formats for movis etc., will be, but their capabilities for playing back recorded TV content from cable card devices is not a matter for speculation, they will play your content anywhere on your network. Reviewing the Ceton Echo Extender thread would give you a better idea of the pluses and minuses associated with these devices. Remember though, a lot of what is in that thread is just speculation as the actual device has not been relaesed yet (due out by the holiday buying season this year).
All that said, I currently distribute cable card content about my house with WMC PCs based on intel i3 processors. Each one costs somewhere in the range of $400 to $600 depending on capabilities. I find this works very well for me with the exception of HBO (et.al.). My movie, picture, and music libraries (stored on a Windows Home Server) are available at all of my TVs and extremely easy to access and use through the WMC interface.
I hope this helps...