Is Apple about to beat Microsoft in total revenue?

What once seemed impossible may be about to happen: This week, Apple may surpass Microsoft in quarterly revenue for the first time ever. It's yet one more piece of evidence that that age of the PC is fading, and the age of mobile gadgets is the future.

Apple will report its quarterly earnings on Tuesday, and then two days later on Thursday, Microsoft will report its earnings. There's some evidence that Apple could beat Microsoft in this quarter, says Andy Zaky in Fortune.

Zacky notes that analysts who were polled by Thomson Reuters expect that Apple will report about $14.62 billion in revenue for the quarter. He notes, however, that "Apple regularly beats consensus estimates by quite a large margin and that actual results will come in well above the consensus." Last quarter, he said, Apple beat revenue estimates by a whopping $1 billion. He adds, "Apple has regularly beaten consensus estimates by well over 35% each quarter over the past year."

Zacky then quotes Financial Alchemist's Turley Muller saying Apple will report $15.15 billion in revenue for the quarter.

As for Microsoft, he points out that analysts expect the company to report $15.26 billion in revenue for the quarter. So that means if Microsoft comes in at less than analyst expectations, and Apple comes in at over Muller's expectations, Apple will beat Microsoft in revenue for the first time in a quarter.

Either way, Zaky believes, "Apple will likely far surpass Microsoft in revenue for the entire 2011 fiscal year."

This doesn't mean that Apple is a more profitable company than Microsoft, by the way. Microsoft will still beat Apple when it comes to profit. Analysts expect Microsoft to report $4.1 billion in net income for the quarter, compared to $3.1 billion for Apple. Microsoft relies on more mature businesses than does Apple, with higher margins.

Still, revenue is revenue. The iPod, iPhone, and iPad seem to be overtaking the once-mighty PC. And it may be that eventually, Apple will overtake Microsoft when it comes to profits as well.