Is this a question about hooking up to an HDTV?
If so, buy any card with an HDMI output. If you need a gaming card that's a lot more complicated as you may need a better Power Supply as well. Otherwise and HD6450 is an example of an inexpensive card (make sure it does have HDMI output).
Then you have to set it up properly:
1) CCC (Catalyst Control Center)
2) HDMI setup-> 1080p_NTSC@60Hz (typical)
3) fix OVERSCAN
4) change AUDIO OUTPUT to HDMI