Telin, let us know if you hear any post beeps. I had a problem when I built my computer, wouldn't post or output video. Ended up, I had f***ed up my CPU when I installed it. RAM is another possibility if it's not posting, along with the video card as a third possibility.
I'd start off by checking to make sure that everything is seated properly, even if it means taking it out and reseating it to make sure.