USB Flash Drive dismounting from CMD?

Hay guyz,

Is there a way to dismount a USB flash drive from a batch file being run off of said drive? I'm hoping for something I can run from the command prompt - I can't use any external software (nothing that doesn't come with windows XP). Also as a side question, is there a way to get the drive to automatically run something (like via autoplay) without popping up that stupid multimedia box first (the one that says "Open files for viewing in explorer", "Open via media player", "Take no action" etc.)?

Thanks.

NTFS kills flash drives with it's "lets update and overwrite the file just cuz the user clicked on it in explorer" attitude.