im sure if you factor in :
the cost of your tv, amp, speakers, mac book, magnetic storage, the mac mini would be a small fraction of that as a complete system.
and, if you factor in your time and 'fiddling about' you save an awful lot going for the mac rather than something else, especially seeing as you already have a mac.
Not sure how well front row works in practice, but CMD+ESC brings up a great browser for your system. It's right there, already. Especially if you use itunes a lot.
The alternative is as mentioned the Revo PCs, or an mini-ITX system, you can get/build really sweet setups, but again, they are generally pricer than the revos but less than the macs.
What about an older gen mac mini?