Maksym, some pointers>
1. an upgrade from 530 to any of the more recent processors would make a lot of sense. now, games are coming out with good threading support for more cores like BF3 multiplayer can utilize 4 threads. Its better to share those threads between as many cores as possible. that means four physical cores will trump dual hyperthreading cores.
2. upgrading to a 6300 opens up some upgrade path for you as piledriver's successor, the steamroller core would also use AM3+ socket. It will outperform the 530 by a huge margin. This would require you to buy a motherboard as well.
3. your current mobo is socket 1156. All processors for that socket have been discontinued for a while and it would be hard to find them for a cheap price. if you can locate a sub $130 i5-760/750 that'll be great for you.
for second and third gen core i5 processors, you'd need socket 1155 mobo with processor. this combo will probably be costlier than 6300 and AM3+ combo.
the order of your search should be core i5 750/760 > 6300 & AM3+ mobo > core i5 2nd/3rd gen + LGA 1155 Mobo.
good luck
-satyam