Alright, so first of all, I know nothing about computers so please talk to me in a language I understand.
Ok, so on my computer, shaders works terribly slow, a lot of games are slow or super slow, and I want to upgrade my computer.
I have a 2GB RAM, apparently, and my graphics card is NVIDIA GeForce 7050 / NVIDIA nForce 610i.

What do I need to upgrade to be able to play good games with no lag and have shaders with no lag?

put a intel i7 and a NVIDIA GeForce 9800gt.

What's an intel i7 for?

I really have no idea how it works.

is a very powerful processor

That's a CPU. It's most likely not really necessary, and probably won't help as much as luigy69 may be lead to believe. Very few games rely REALLY heavily on it, to the extent that a bad CPU will actually lag it. Most games run just fine on midrange CPUs, and those that don't were released quite recently.

The most important thing for shaders, and for most gaming in general, is the GPU, albeit your 2 GB of RAM could be bumped up to 4 without any worries. (Don't add more RAM, replace it completely. It's much easier to replace all of the RAM than to try and work out compatibility.)

I'd recommend you go higher on the GPU spectrum, since you can get better cards that the 9800 GT for very reasonably higher prices. The GTX 460 is a very solid card in that respect, and has a price in the $150 range. Of course, double check that your PSU can actually handle a newer GPU.

but praeter wants to play others games too.
so he need a good processor too.

Again, processors have very little impact on the vast majority of games. This is a simple fact of life.

no, the processors are the speed of computer.

No, they're not. Most processing requirements of newer games are done on the GPU. The only reason shaders run slow on most computers is because CPUs are not powerful enough to compute them reasonably. There is no CPU solution that can perform shader computations more quickly than even a midrange GPU.

Sure, CPUs affect the speed of sequential arithmetic and whatnot, but most games don't rely on that. Most games rely on heavily parallelizable graphics computations. The only effect a CPU has on those is how quickly they can send computation requests to the GPU, and even a weak CPU can gain a very significant benefit by acquiring a better GPU.

Alright, only for Toribash then, what should I get to just have my Toribash running perfectly with shaders and raytracing? And how will it change things? For example, if I get a new RAM thing, will that like delete all my files I have on right now?