My primary goal was to protect my mac login with a password, but since I hate to enter passwords I've tried Rohos key program. The install and USB stick setup was easy. Login works very well - it just autoenters my pass into mac os login box. exact what i needed. when i open my macbook I see locked screensaver, upon usb key insertion rohos autoenters my passw into unlock window. then I can remove usb key. I know that I need close the lid in order to lock my mac. thats easy. If I forgot my USb stick somewhere I can just enter password manually (to use this optin set a check 'use locked screensaver' ). For a two week of usage i dint encountered any issues with it.
Mac book pro 15", mac os x 10.5.5, Kingston USB flash drive.