I have 3 fallout games.
Fallout New Vegas is the best. It is awesome, one of the best RPGs I ever played.
Play it!

Fallout 1 is good. You can see were it connects to FO:NV.
Fallout 3. Good. Nowere near as good as FO:NV. Does'nt actually look like it belongs to the same series in many things.
No, there is not a new one coming out in january.
You can play them in any order you want.
Just play the games you have now.
You can get Fallout 1 at GOG.com, for free.