I would strongly consider these PSB speakers, T45, T55 and B25's

http://saturdayaudio.com/picturepage...07-29-2009.htm

Much better than the Polks. And just remember, any book shelf speaker you buy will need decent speaker stands which will run $80 and up.

For the rear channels I would do the PSB B-15's and for the Center the PSB C40 or C60.