Hey Pedro!
Got a solution for your photoshop problems!
try GIMP, its completely free, do the same things with photoshop, its lighter than PS...its perfect!
No iam not working for them and try to advertise it! ;-) but i was using it for a while and i was really happy with it!
http://www.gimp.org/
and its available for all platforms! Windows - Mac - Linux....
cheers!