CPU running on lower Ghz (considering upgrade)

Awildmagikarp

Honorable
Dec 22, 2013
16
0
10,510
So my e6550 (2.33ghz, 1333mhz FSB) is running at 1.86GHz on my P5LD2-X/1333
I know my Mobo doesn't support 1333mhz FSB but the ASUS website states I can overclock it, but I don't feel like doing so.
So I'm thinking about getting a Core 2 Duo E7300 (2.66GHz, 1066mhz FSB), but I will be losing 1MB of L2 cache.
So my question is: does having 3MB of L2 and 2.66Ghz be better than 4MB of L2 with 1.86GHz?

EDIT: If I were to get to a 1333 FSB, what would I have to overclock? CPU,RAM or both?