Light up the candles. Windows 7 turns 1 today. Happy birthday to an OS that debuted in the worst of a recession and went on to exceed expectations, racking up approximately 240 million licenses to date.It also successfully shut the door on Windows Vista, Microsoft's embattled follow-up OS to the still-thriving Windows XP. Vista struggled throughout its lifespan and Microsoft desperately needed a reboot to stop the sneers: Windows 7 did just that.Will it be able to keep up the momentum? Probably not. Windows 7 has far surpassed where Vista adoption was at after a year, but industry analysts are reporting a slowdown in enterprise migrations as the economy sputters and businesses satisfied with Windows XP drag their feet.\n\n\nA PC sales slowdown is also in the forecast for the second half of 2010. And then there are tablet PCs, an emerging segment where the iPad rules and Microsoft still has no presence with Windows 7.Nevertheless, Windows 7 has accomplished much in just one year of life. It made inroads at enterprises who passed on Vista and were ready to refresh Windows XP; its operating system market share reached 17 percent last month, according to Web metrics firm Net Applications. It is running on 93 percent of new consumer PCs, and is being sold by 100 percent of Microsoft's OEM partners. Microsoft is predicting that it will sell 300 million Windows 7 licenses by the end of the year.To honor Windows 7's better-than-expected first year in the wild, here's a look back at four CIO.com stories spotlighting seven enterprises migrating to Windows 7.\n\nWindows 7 Early Adopters Say Virtualization Key to Rollouts (June 11, 2010)\nEarly Windows 7 adopters Expedia and Continental Airlines share rollout lessons learned. Here's a look at their secrets to smooth deployment, starting with smart use of virtualization.\nBMW Calls Windows 7 Rollout Smooth Driving So Far (Jan. 6, 2010)\nGerman car giant BMW is racing to the next phase of its company-wide Windows 7 migration faster than expected, having won over internal skeptics. Here's a look inside their rollout to date.\nWindows 7 Launch: Early Adopters Eager to Bid Farewell to XP (Oct. 23, 2009)\nAt the Windows 7 launch in New York, Windows 7 migraters Holland America, Del Monte Foods and Starwood Hotels discussed cost savings, testing strategies, and security hopes and fears with CIO.com. One consensus: Windows XP is on life support.\nWindows 7: Why I'm Rolling It Out Early (May 18, 2009)\nWhile many IT organizations say they're in no rush to roll out Windows 7, the City of Miami, already a Vista shop, won't wait. Here's a look at the IT plan and reasoning. Shane O'Neill covers Microsoft, Windows, Operating Systems, Productivity Apps and Online Services for CIO.com. Follow Shane on Twitter @smoneill. Follow everything from CIO.com on Twitter @CIOonline. Email Shane at firstname.lastname@example.org.