I have my Laptop plugged in my TV via HDMI (Vaio and Samsung) and it's crystal clear. As  good if not better than any monitor I've ever seen or owned. I assume it is also still a much cheaper option, as last time I bought a very large widescreen monitor it cost the earth.

However I used to have an acer Laptop and that looked bloody awful on a TV. So I'd imagine reading up heavily on the graphics card beforehand will help.

Between myself and the rest of my family we own at least 5 different sizes and models of Samsung HDTVs and they are all great with whatever you plug into them, in my experience. iPhones/Digiboxes/DVD & BR players/HDMI PCs & Macs/old PCs/Hi-Fis etc

If the resolutions and the hookups are the same, I'd say there's no difference. 

Generally, I'd say it comes down to DVI and Display port over HDMI and higher/less common resolutions.  1080p for a computer monitor (especially a big one) is quite low.

It used to be the case that here in UK you had to have a license if you had a televison tuner (it didn't matter if you used it or not). Which is why my VHS machine is a car video player.

But now you can have a tuner and as long as it's not connected to an aerial ever you are okay.

So even that regional reason has gone.

Aren't monitors cheaper?