To use Lion, make sure your computer has the following:
Would Also Recommend that you do a Bootable Clone Backup of your current Hard Drive Before attempting any Major Upgrade...
By far the easiest way to make a Backup, is to use something like
or CCC http://www.bombich.com/
Also... For Lion... Check the Compatibility of Third Party Applications you may be using...
Lion is a hungry beast...Would also suggest that you Increase your RAM to the Maximum for your computer...