@MikeD and Fernando1: I registred just to thank you for great help you provided with this issue on XP. Zip file provided by Fernando1 for 32bit systems worked for my ASUS K50AF - now it is in AHCI mode working like a charm together with windows 7 ). I maneged to have it done without a single problem following MikeD's hints/tutorial and using Fernando's linked driver. Just to mention that afterwards beside catalyst driver from offcial ASUS site Southbridge driver from ATI should be installed in order to find SM bus controller. In ATA mode i had no such "problem". Great job guys!
