Here's what i have been using for more than a year now. It works well with media center. It functions as PVR and DVR. It records 2 shows at time. Or you can watch and record at the same time.
It records HDTV and regular TV format. The typical HDTV recorded shows/movie is ~ 5Gbyte per hour.
It works well with XP and Vista-64. I dont expect it to have issues at W7 but i'm not in the position to provide anything more than what i said.
Below is the newegg site..http://www.newegg.com/Product/Product.aspx?Item=N82E16815116036
Below is the webpage http://www.hauppauge.com/site/products/data_hvr2250.html
I tried other boards such as ATI 650, Pinnacle HDTV, Hauppage 1600/1800. The hauppage 2250 is the best.