Im new to here and need some help in regards to getting a new gaming PC for me.

My budget at maximum is about 2-3k.
Reason is I bought my PC about 3 years ago and I spent that much and it has lasted me this long with out any issues what so ever (reason I need a new one is I am giving my old one to the wife).... so with that in mind I wanted to do the same this time around and get something descent so it will last me another 3 odd years

This PC will be purely for gaming. And the usual checking emails and streaming movies etc which i don't think uses up that much resources.
I don't know what I need since there is i3, i5, i6, i7, quad cores lol very confusing. But just to give you an Idea I play multi player online games only (e.g WoW, Lineage 2 etc).
Anyways If you can give me some feedback in regards to parts or point me in the right direction it will be great

Thx