i would like to know the best graphics card for my pc

Yea you really need more ram and a better cpu. 2 gb of ram?? Like 4 is the minimum now a days. I would recommend just buying a whole new computer but if you "just" want the graphics card you might be able to get a gtx 750. Pretty cheap and it performs ok.
 


Ram and VRam are entirely different things. Having one will not affect the other.

However I do agree you definitely need an upgrade from 2GB of ram. I'd suggest adding another 2GB stick if your motherboard can support it and adding a low powered graphics card such as the ones mentioned above. If you plan to upgrade past that I also agree it's better to just save for a new system.
 
You are asking what kind of running shoes to put on grandpa. They'll look good, fit fine and will work around the house. You can't expect just because they are running shoes, grandpa will sprint to the mailbox.

Adding even a low power gpu such as a r7 260 or gtx 750 to your pc will have the same results. The ddr2 for your board is more expensive for 1Gb, than for 4Gb of ddr3. Your processed is dated enough that it will assuredly suffer during more modern games, dragging down any performance from the gpu. Unfortunately, you are a victim of supply and demand, there being little demand for dated equipment, the prices get jacked high.

Honestly, a budget pc from Walmart or Costco will get you better performance, even with just integrated graphics. Sorry if that sounds blunt, but for what you'd spend in upgrades to revitalize your current pc, a Walmart cheapie would be cheaper.
 
as long as you change your graphic card you will see improvement of your gameplay and if you change it to high end GPU you will not get full performance of the GPU because of your CPU.I suggest you get GTX750ti or R7260X and upgrade new pc as soon as posible.If you change a low end GPU i think it waste money because you PC really going need to upgrade next year or 2 year more in my opinion.But you still need to remember games that need quad core CPU you still cant play or you will run all at low including resolution if you lucky enough.