I don't have the 550, but I do have the X600, and you must install the ATI proprietary drivers. They do support hardware 3-D, but nothing much else besides dual monitors and TV out. Really a big waste of an expensive card for what I'm doing. You also will have problems during install if you try to use the 550. Use a common card, then drop the 550 in after installing the drivers. Sam -- Snowman