keep essential files on my laptop and desktop in sync so Im kinda running a DIY raid 1 array 
 
also have a  month old backup CD for emergencys (after format, network card drivers for laptop are 5MB 

 )
"essential" files tally up at around a gig + games take up the rest
725MB for install files and unsorted
40MB for my documents
250MB for funny apps/ really old games and funny misc stuff *pics, texts, wallpaper etc.)
that, and office CD and a windows CD is ll I need for a fully functioning computer