Update 2014-09-20: Try the Consolas font instead of the default Courier New. It’s slightly smaller but still quite readable and permits a narrow 80×40 window which I can lay out side-by-side 3 times on my desktop (1920×1080) without overlapping. That’s something you can’t do with Courier New at 80×40. Give it a try under Putty Configuration > Window > Appearance > Font Settings.
Better Colour Schemes for PuTTY
Check out the igvita.com colour schemes for putty. They’re very good and a big improvement on the default colour scheme. If I have to use a terminal on windows, putty is it and these colour schemes really make a difference in the usability of the terminal.