Would dvi be better than hdmi?
I've got a 13" and an Acer H213H monitor, which I picked up from Future Shop for CAD$212 total (~$190 US). It's got 1920x1080 resolution like some physically larger displays and looks fine in my opinion. If you're just looking for more screen space, it's a good option.
I use my mac to watch tv shows and movies on my 40" Samsung HDTV and HDMI seems to be fine, Mini display port dvi --> DVI to HDMI adapter --> Hdmi cable.
The monitor would be used as my MAIN display for my mac. I have a apple wireless keyboard and mouse but i just want a bigger display for when i use my macbook at home.
Would dvi be better than hdmi?
Fewer conversions, so it's your call. You can just get a Mini DisplayPort-HDMI adapter, though.
i already have the cables i stated above. I was just wondering if the picture would be better with DVI direct?
I can't imagine that there would be a difference. Your signal is completely digital all the way through, so there shouldn't be any degradation.