RAM memory

I plan to upgrade my RAM, cause I have only 2GB. Now, it won't even open, when it does just base game loads,packs don't. Does anyone play Sim with all packs with just 4 GB or I should upgrade it to 6GB?

I play with 4gb ram and its ok. But I don't know how it will be in the future with other EPs . Sims 3 had 11Eps and we are now just on 4th ep. Now its already 4gb minimum system req and who know how much it will be needed when we get 6-7 more eps.

4 GB here as well, no problem.

Along with Pets?

Jup. So far everything works great. But because of all possible  future Game packs,
I will probably also get additional at a later stage, I am running it on Laptop, not even high end laptop.
If I run that little program that tells you if your Computer is even able to run the game, it keeps on telling me it is not. CPU is only 1.9Ghz.
But it runs without a hitch. Settings on medium, most of them. No Laptop mode. Maybe I am just lucky.

16GB for me, no problem.    

But seriously, in general it is: the more RAM the better. If you have the chance to purchase more/better RAM modules, then it won't hurt you.