Imac laptop

some guy gave me his imac g5 with 30gb hard drive to figure out how/what is taking up all the space.  There is 3gb left out of 27.8gb.  He wanted me to delete all the extra apps that came with it but I don't think its worth the time.  How much space does an OSX install take?  Do multiple profiles affect the space (i.e. duplicated shit) I've never used OSX before.

A good way to reclaim some space is to delete the localizations he doesn't use. There is software for that.
And OS X install takes about 5~6GB I'd think.

I recommand using the whatsize application ( http://www.id-design.com/software/whatsize/index.php ) to find out where is all the data hidden.