Driver software problem

Hello,
i have a problem whenever i connect my sony ericsson phone through usb with my pc it shows firstly that installing device driver software but then it shows up that its missing and to provide the cd i got with it but then too it doesn't works out... the same thing happens when i connect my sony walkman , it shows its installing the driver software but then the same dailouge box appears ..... please help me out with this problem i cannot transfer any files to my mp3 or even cannot charge it and the same is with my phone it doesn't even works if i make it work on file transfer mode... please tell me which driver is missing and how to fix it up.... and i am currently using vista.