Hey guys. I'm going from Lion to Mountain Lion like many of you, but I was wondering what i could do to clean up my MacBook Pro before making the jump to the new OS. Are there any tools (preferably free) that I can use to clean up my Mac? Maybe get rid of duplicates and chart out what my biggest files are? I still have about 100GB left in my hard drive, but i've been noticing my Mac acting pretty laggy recently. Any suggestions? Thanks.