In my opinion, a good IT Department starts with the people. You could spend millions on high-end infrastructure and application tools, but if you are working with a bunch of derelicts, it will be money wasted.
Conversely, you could be forced to use middle-of-the-road (at best) equipment/apps; but because you have great staff, get much more out of it than anyone would anticipate.
If I were to asked to come up with a document on what makes a good IT team, I'd start by listing off various personality traits that seem indicative of good IT workers:
Innovative
Self-motivated
Logical thinking
Non-Linear/Creative thinking
Practical
Etc, Etc, Etc.
Once you describe the types of people that make a good IT department, you can move into the tangible 'why they make it a good IT department' (better ROI, better security, etc, etc).
That's my 2 cents, though. I'm sure others will come up with different answers that have just as much if not more merit.
Best of luck!