for normal usages/daily applications i3 will be enough for at least 3-4 years.
i am not a gamer but i think most titles will run fine on medium-low settings with 6770.
That was not my questionGet AMD a6
or AMD X4 965 BE if available they good processor and can be overclocked easily.Amd X4 is 5k I guess if available.
core i3 has hyperthreading meaning it has 2 real cores & 2 virtual cores(as seen by operating system).it will perform faster than 2 real core processor like pentium G620(which has no hyperthreading) but lesser than 4 real core processor like i5 which has no hyperthreading(i7 has hyperthreading so it is priced higher than i5 because it acts as 4 real cores+4 virtual cores so total 8 cores to an operating system).
P.S. in my opinion if you are spending 7k on i3 then if possible it is better to spend 10k on i5 because with just 3k extra you will get a more future proof processor.