[users] compatible?

[ELENA SAVIN]

Hi, how are U? I been using Microsoft office 2007 for almost a year, got a lot 
of files (from school) I heard that OOo is pretty good and I want to give a 
shot, but, Will I be able to open all those files from MO 2007?, and more 
important: I do not know if my friends are going to be able to read and open 
this new format/extension?   It is totally compatible?
Regards...