Free software for intermediate learner? I'm at about 1600 level, roughly speaking, and I need a good software with lots of options to keep me interested in learning chess and improving myself.  I've heard of different ones, including SCID, Lucas, Arena, and recently someone recommended Jose.  Do you know of any other programs or what do you think of these?  I'm not computer literate so please dumb down the explanation for me.  

For instance, someone said that Arena is closed source but SCID is not, and that SCID is more of a database program.  I don't know what those things mean or if that makes one better than the other.  Jose was someone's solution on a website to someone wanting to combine the best of SCID and Arena, for instance.

Thanks
Why not solve more Chess puzzles? That will definitely help you. 
There are many freemium model chess sites out there.. 

My favorite is Chessity
Others in this list are: 


Chess.com
Chess Tempo


[This list is endless. Other may have suggestions too.]

I'm afraid that playing against computers might defeat your motivation, because they are very good and beat humans without mercy. 

I would also recommend playing online with other human folks. 
I use Playchess