Is 4.00 gb ram bad for minecraft? And what graphics card best for fixing lag in minecraft?

I just checked how much i have. Is that bad for minecraft? I have a lot of lag. I'm planning on buying a new graphics card because i have an old one for like 3 years. So what graphics card is good and not too much money? Don't tell me to stop playing or that i shouldent buy it because i only play minecraft please. I'm playing every day and i need a new card