This card reader works flawlessly in my early-2008 (Penryn) MacBook Pro. I never take it out. I use it routinely to read the 2 GB SD card from my camera, and I've also used it to write MP3 files to a 1 GB SD card for use in my car. Have not tried other types of memory cards. I have not experienced the sleep problem that other Amazon reviewers have mentioned. Perhaps that issue was fixed by an operating system update. There are no drivers to download or install; just pop the card into your MacBook Pro and forget about it until you need it.