H61 have just two memory slots. Get a H67 maybe in time you will nedd more memory on your pc.
H67 allows for use of Sandbridge's (and probably Ivy Bridge's) iGPU. H61 is basically the same but with less features (no RAID, less SATA ports, less PCIe lanes, etc). P67 allows you to overclock your CPU. Z68 enables the features of both P67 and H67 and SSD caching.