dedicated video memory only applies to internal video cards in motherboard which you are not using in any case, 8gb is fair for playing games considering your cards has little ram itself for processing graphics. that said. yes the GT210 is definitely your weakest link here, and you need to be mindful when you are going to upgrade that video card of your power supply capabilities cheap or not, as video cards with more power need more wattage to run.
Suggestiosn and this will all depend on your budget of course in order I would upgrade the following items (just to give you an idea)
Power supply to 500w
Video card to GTX 660 or better
Upgrade your memory to 16GB
Upgrade your CPU to A10-7890K (max this motherboard can do)
this can be...