First I would solve the biggest problem I believe Microsoft has at the moment which is their "Identity"...
I would reposition Microsoft as the "Creative" Company.......
This will begin with 4 major acquisitions:
Small: Vimeo & deviantART
Adobe: Adobe provides a large array of products that many artists and professionals swear by, and would be the perfect company to jumpstart this new creative mindset. This would also address another one of Microsoft's major weaknesses....necessity....Microsoft products are just no longer seen as being essential by the eyes of many consumers, outside of Office and their enterprise software of course. This acquisition will guarantee that Microsoft will be at the center of our "Creative" lives, and with the Creative Cloud, Adobe is already set to execute on Microsoft's current Cloud/Services centric strategy.
Anyone who purchases a Microsoft Surface device will receive a year of "Creative Cloud" on the house.
Wacom: Wacom is the industry leader of graphics tablets and related products. After this acquisition I would simplify their product line and bring it under the Surface brand. This will greatly expand the Surface family of products and repurpose the brand for "Creators" while also keeping all of the current functionality that appeals to professionals & consumers now.
Every Microsoft Surface device includes a premium "Pro Pen"
Vimeo: This video sharing website will be key to the rebranding of Microsoft and will aid in greatly improving public perception of the company. Vimeo is seen as an industry darling to many. This is not a YouTube competitor, this is a site that has historically focused on shorts, animation, and overall artists, under the new ownership of Microsoft it will continue as such. This acquisition is to provide "Creators" with a platform to publish their work.
Anyone who purchases a Microsoft Surface device will receive a year of "Vimeo Plus" on the house.
deviantART: is an online-community focused on showcasing various user-generated artwork. Much like the Vimeo acquisition this will provide "Creators" with a platform to publish their work as-well as inject a much needed "Youthful" appeal to the company.
Anyone who purchases a Microsoft Surface device will receive a year of "deviantART Premium" on the house.
Why this assortment of companies?
The combination of these companies will provide an end to end experience for Microsoft customers.
Scenario: You create your work on a (Wacom Powered) Microsoft Surface device using Microsoft tools (Creative Cloud) then publish and monetize through a Microsoft Network (Vimeo/deviantART)
Microsoft: "Everyone is a Creator"