I'm not sure I understand. Let me try to piece this together.
So you have it hooked up but the image basically looks like crap right now. So your trying to make it HD by setting it as 720p or 1080p. Am I following this correctly?
If that's the case then you may have an overscan issue. Check out this thread:http://www.tomshardware.co.uk/forum/61754-29-asus-monitor-issue
If that's not your problem, feel free to ask.