27" iMac in for Service - Advice

so I have to finally bring my 27in iMac in for this screen going black issue.



My question is without wiping the drive clean what else can I do to secure my data on the drive?



I don't prying eyes looking at my private files/emails etc.



Thanks

via ehMac.ca http://www.ehmac.ca/showthread.php?t=106785&goto=newpost