Yep, Radeon HD 5870 is supported by Win10, it's in Legacy group so that means it won't get many drivers in next few months/years, guess few more and that's it. For non demanding gaming, internet, movies, web browsing etc current Win10 drivers will be more than be enough. Latest Win10 WHQL drivers provided by AMD are 15.7.1 WHQL (7/29/2015), latest Crimson Beta Win10 drivers are 16.2.1 (3/1/2016): Win10 32bit & Win10 64bit