I know this is an old game and I'm not sure if this is the right forum to post this in...buuuut I found a way to increase your Warcraft 3 Resolution. ( I still know a couple of you play DotA out there =) ).
Go to start...
Run...
Type Regedit...
Click HKEY_CURRENT_USER
Then Click Software
Then Click Blizzard Entertainment
Then Click Warcraft III
Then click Video
You should see the two files named
Reswidth
and
Resheight
Click Reswidth and make sure Decimal is checked/marked.. and enter your width resoltuion (Ex 1680x1050 = 1680)
then exit out and click Resheight and make sure decimal is checked/marked and enter your height resolution (Ex 1680x1050 = 1050)
Exit out of all of that and start up warcraft 3 and there you go =).