Mavrick??
My Advise is not to get tempted by the word "free" and download Mavrick.
1- Painflully slow
2- Not easy to un-install (Don't know why). Its like you in then no way out
3- ...etc
Had to find the original Mac CD to un-install Mavrick but then had to copy every thing to an external drive......despite all that effort, I lost heaps of valubel info from the updating process. Avoid!
Glad to be back to some speed where i don't have to wait minutes for my computer to start loading pages :-)
spending a couple of dollars will give you a peace of mind.
I upgraded from OS X 10.6.3 by the way.
Cheers