My first ht! Not much room

[andy149n]

I recently just got a new (my first!!) hdtv and now I've become obsessed with wanting to have a better sounding system. Since this would be in my bedroom the most I would be able to fit in here is 5.1 (if that). My father is big into ht's and was basically telling me what to get and I needed some input before I go start finding speakers to audition and spending money on a receiver. He suggested I pick up a sony STR-DG920, 2 Polk Audio Monitor 50's, and Polk Audio PSW111 8 in. sub. Seeing is how this is my first time diving into this I wanted to get some opinions on if this would be a good starting point. As far as the other 2 speakers he has a couple sony's that he is planning on giving to me.