Microsoft may be the behemoth monster 800-pound gorilla of software, whose Windows and Office products are nothing short of Golden Gooses. Or Geese. Or whatever.

But it’s interesting to hear how its leaders view themselves. To hear Chief Executive Steve Ballmer talk about Microsoft, you might think it is still the underdog startup it was 33 years ago when Bill Gates and Paul Allen started the company . Or the sapling it was when Ballmer joined in 1980.

People are underestimating Microsoft. Yes, we make mistakes, but we come back and learn from those things.

His comments were made during an event today to mark Gates’ stepping down from day-to-day operations.

Can you blame them? Someone once said that as we grow old, we never lose the sensibilities of our youth: the awkward nerd may always be raring to fight the big bully. Maybe that’s why Ballmer, after some 28 years at Microsoft, said this about IBM:

We went toe-to-toe with the biggest, most powerful computer company in the world and we beat them. Windows vs. OS2.

Sure enough, the David vs. Goliath story came out with the right ending. 

And they showed (again) a funny “farewell” video about Gates, the world’s third-richest man, warming up for a “fight”, with the help of buff actor Matthew McConaughey, who while steadying a heavy boxing bag for a sparring Gates, said:

“Steve Jobs! (Jab); Larry Ellison! (punch); Nice, a head shot.”

Maybe someday that little Microsoft will be a contender…

(Here is an earlier version of the video, first shown at the Consumer Electronics Show in January, without the boxing reference, from MSN)

IBM Chief Executive Sam Palmisano gloated to an audience of companies that sell its wares that Big Blue would make it through the current economic downturn with flying colors, since it is old and experienced. Riffing on the idea of age, he compared his tech behemoth to Internet star Google Inc, whose CEO Eric Schmidt was about to join him on stage in LA.

“It’s interesting when people think about companies like IBM and Google. I mean, we couldn’t be farther apart. We’re old, they’re young, we’re kind of boring, they’re innovative, we’re slow, they’re fast, we’re fat, they’re skinny,” Palmisano joked.

“How could you guys possibly work together?” the IBM chief asked himself. “I don’t know!” (The conclusion was that they worked well together, after all.)

Oddly enough, Palmisano may have edged out Schmidt on the cool factor though — the Google chief showed up in jacket and tie, while Palmisano strode around the stage with an open collar.

 (Reuters picture of Schmidt is from a different event, same look)