Mac Geekery

ye… i got a new macbook core 2 duo 2ghz 2gb ram 80 gb hd and i have a few quesions – first of all by creating an alias for external media u are able to view the external media without the dvd or cd if im not mistaken and by using an alias in this form does this take up hard drive space? Additionally, if i have media fiuled on an external hard disk how can i directly view them from front row without copying them to my hard drive?