It's hard to believe that you've managed to survive this long without StuffitExpander. It was designed specifically for the Mac and is completely invaluable. So much so that I thought it was pre-installed with every new Mac shipped. Have a look in your Applications folder - you might just have to do a quick install - but if it's not there you can download it for free at
http://www.stuffit.com/mac/
Its such a pleasure compared to 'labour-intensive' winrar. You double click or drag the first archived/zipped file and that's it...it does the rest.
This from Apple's website at
http://www.apple.com/downloads/macosx/system_disk_utilities/stuffitexpander.html
Easily expand and decode all the files you download from the Web or receive in your email. Access StuffIt files, uncompress Zip archives created by WinZip and other zip utilities, decompress tar, gzip and bzip archives, and more. Just drag, drop, and you’re done! From BinHex to Zip, StuffIt to MIME, Expander accesses more formats, in less time, with zero hassles.
Your life's about to become a whole lot easier, my friend.
s