I think it's the dh55tc that's Micro. The hc is atx.
OOPS! you are correct.
The difference is then mainly for the onboard graphics support.
You might want to consider the i5-670 and the H55 at the same price point if you do not need 4 cores.
The 670 is clocked at 3.46 with turbo up to 3.73.
How much do you really need 4 full cores?