When you connect your hd flatscreen to your computer with the regular pc input will you get hd picture? or do?

Using a VGA cable you can get whatever resolutions that both your TV and screen support, anything over 720p, which is 1280x720, is considered HD. To get the best picture, set it to your TV's native resolution, that way it is generating one pixel for every pixel on your screen, and not having to convert it, which lowers the quality. Most HDTVs are 1366x768 or 1920x1080. If it is a 1080p set, it is the second one. HDMI will give you a better picture because VGA (what im assuming you are calling the regular PC input) is analog. The signal can degrade due to quality of the cable, interference, etc. It won't be as sharp. HDMI is digital, so it sends digital information, 1's and 0's, which the tv decodes. Either all the 1's and 0's get there and you have a perfect picture, or they don't and you have no picture (or something obviously wrong like lines or flashing). If the picture looks right on HDMI, then it is perfect. There is no in-between quality. That is why a $4 HDMI cable is as good as a $400 one. It works perfect or not at all.

Depends on your graphics card and the connection: vga/s-video/vga/dvi/hdmi