In the past I've read that Sapphire's drivers are the preferred choice (possibly even a requirement for trouble-free operation) only for the 4850x2 and 4870x2 card models due to Sapphire's own tweaks on these less-common, specialty cards. ATI's standard Catalyst release should be fine for any other model, including yours.
In looking over the links on Sapphire's site and going through a few models, the drivers seem identical to those from ATI. Download both, right click, select properties, and compare the details. I saw no difference in the two I downloaded, other than Sapphire's was in .zip format, which is stupid because it's the exact same file size as the one from ATI... LOL