I first tried this on my mini, which I've since traded for an iMac. I prefer the look and feel of Front Row, but have two major gripes: no support for AVI files, and even after today's update, movie trailers take FOREVER to load up. MediaCentral, on the otherhand, does support AVI files, and loads up movie trailers (giving me a much greater selection AND allowing me to pick size and SD or HD) instantly. I have cable internet, so there should be no reason why Front Row takes so long with loading trailers.
Anyhow, MediaCentral addresses my two main issues... but I'd much rather see Apple address them... Front Row looks better, I think. Sorry.