I tried using an ASUS My Cinema U3100 Mini USB ATSC PLUS tuner and it was a bust on MythTV. Spent hours trying to load drivers from the ASUS website and source code and compiling it, nothing worked. It appears as though they made a non-Plus model at sometime and that supposed to work well but not the Plus model which is based off a different chipset, the af9035. I've been working with Linux since version 0.9 and know it inside and out, so while I could eventually have figured it out, life is too short. It turns out the Linux driver that comes with it is very specific to the Asus Eeepc netbook and won't work on anything else.
But it does work fine with Win 7, so Media Center will be my choice as it's cheaper for me to pay for Win 7 than buy another solution and hope it works. Also, whilst playing with MythTV I found out that free does not mean no cost, just means you are free to pay a service for a guide and that's $25/year where with Windows the guide is free.