The markets have sustained yesterday's rally as investors hope for the best following Russia's move to formally annex Crimea. While the situation is still in flux, the Dow Jones Industrial Average (DJINDICES:^DJI) has made the most of investor optimism, rallying higher by more than 107 points as of 2:30 p.m. EDT. Microsoft (NASDAQ:MSFT) has surged 4% to the top of the Dow today. Let's catch up on what you need to know.

Will Microsoft shake up mobile?
Microsoft's new CEO Satya Nadella is looking to make a big impact in the tech world this month, according to sources cited by Reuters and other news outlets. The reports say that Nadella plans to roll out Microsoft's Office platform for Apple's iPad on March 27. The move could help Microsoft gain much-needed traction in the tablet market, where the company's Surface has found only modest success so far. By expanding Microsoft's powerful suite of software to one of the market's most widespread tablet lines, Nadella could both delight investors and carve out a lucrative niche in the tablet segment without counting on a market share blitz from the Surface.

This would be the second time Microsoft has turned Office toward Apple's mobile products, as the company released a mobile version of the software for the iPhone in June 2013. Analysts believe Microsoft could be missing out on huge revenue streams by holding back Office and its software prowess from leading mobile products such as the iPad. With mobile's growth driving back the PC market, this move -- if sources are accurate -- would be smart Microsoft's long-term future.

The Dow's software king made news today on the hardware front as well, announcing that its new Xbox One entertainment and gaming console is set to release in 26 additional international markets this September, including India, Japan, and the Netherlands. The Xbox One's launched last year with a strong burst of momentum, but it trails rival Sony's (NYSE:SNE) PlayStation 4 console so far in worldwide sales -- a trend not helped by Microsoft limiting the Xbox to just 13 countries last year. Sony released the PS4 into more than four times that number of markets. Microsoft's move to expand its global reach should help its console close the gap with the PS4 in 2015.

Meanwhile, leading used video game retailer GameStop (NYSE:GME) slumped by 3.5% today after retail king Wal-Mart (NYSE:WMT) announced its intentions to give store credit for used games at its stores. Wal-Mart's stores have taken a beating lately as growth has slipped, and the move's the latest push to light a fire under the company's business as the new generation of video games begins to take hold. While it's uncertain if game customers will embrace Wal-Mart's move to the extent that they helped GameStop surge to the top of this business, the entry of one of America's retail leaders into this niche makes the GameStop's dominance all the harder to maintain in the coming years.

Dan Carroll has no position in any stocks mentioned. The Motley Fool recommends Apple. The Motley Fool owns shares of Apple, GameStop, and Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.