For WoW, I don't think it will matter if you have an i3 instead of an i5. Also, unless you intend to game at or beyond 1080p in WoW, you might want a lower end video card, I'd go for the 6770 or 7750 here unless other games will also be played and 1080p is required. H67 is better than H61 simply because it is more robust. If you're not going to overclock, I say H67. If you will overclock, then Z68.
H61 often only has a 100Mb ethernet port instead of 1Gb, doesn't support faster than 1333MHz memory (although that's really not important), tends to only have 2 DIMM slots, and doesn't support CF, which may be important later on. I don't remember if H67 supports CF, but it probably does.
I recommend waiting for IB to come out and getting an IB i3 or i5 because it will have slightly better performance and lower power usage for the sme amount of money, or at least lower prices on SB i3s and i5s.
However, I do not suggest going down to 4GB of memory, keep it at 8GB.