E5200 is a better choice because of its price. Although of course E7300 will always be better than it in performance, but not by a great margin and E5200 has greater value.
For a good overlocker you'll need something like P5K-VM or MSI P35 Neo, these two are hard to find now and will cost around 7,000rs.
Or theres a new G43 Asus mobo on Galaxy, but I dont know anything about its BIOS capabilities, or you will have to spend more to get yourself P43 or 45, which ever you can afford.