Just received a ROKU 2 XS..I want to hook up to my Sound System. need help

So as title states, I got a Roku 2 XS, and I also have a Sony HT - 550w Sound Bar system and a Sharp LCD. The Movies on my USB Drive are MKV and have Dolby and/DTS and the roku only passes that through

I know I can hook up the Roku to the Sony via HDMI but then how would I get video to the TV since I dont have a HDMI to the TV from the Sony? Or would I just buy another HDMI cable?

Yeah Thanks! I actually tried this when I got home. Worked Great!