For some reason, whenever i start up Real Myst (im running windows XP home) windows says i need a video codec. I go to the website it gives me but i have to pay to get those. It used to run prefectly before on this same computer but for some reason with this game and other older titles the intro videos refuse to play and so it causes these games to crash. Please help...

Ok i can kinda get around that problem, for some reason if you wait 5 seconds after accepting the error the video will play. But for some reason its very choppy. Then, once i'm on myst island, there are certain areas that will turn everything into a slideshow from perfect performance. For example, i can walk all the way down to the clock tower at the other end of the island, but if i even glance toward the little pool with the two sets of pillars, or to the note on the ground, i get about a frame every 3 seconds. What is causing this?

Oh and for some reason the setup program wont let me enable FSAA, even though i know my card can handle it (a radeon 9800 pro).