The answer is "it depends"... HDMI is a finacy little signal, so the quality of the
driver, the cable, and the receiver all will affect it. There are cables that claim to go a couple of hundered feet, but always look at the signal that they are using in the spec,
if any. You can go a lot farther with 1024x768 at 75 Hz than you can with 1920x1080p at 60 Hz. More pixels at more clock rate means more bandwidth. If you have a really long way to go, or have to get the cable through conduit, then a converter that reformats the signal to CAT5e / CAT6 or Fiber Optic is a good idea. If you need HDCP, then make sure that the solution supports it - not all of them do. Also, check to see if the vendor certifies the product to work at the full cable length and image format you are using. HDTV is typically 1920x1080p at 60 Hz x 8 bits per color, but could be at 120 or 240 Hz if you are using 3D, or could be at a higher color bit depth like 10-12 bits per color (aka Deep Color) for photoshop-like applications (this depends upon your monitor
and your graphics card
and your software). Many 'standard' apps only use 8 bits per color, but why not prepare for the future?