The E6700 support 64 bit and you should be able to install 64bit windows with it. You can also find this information from this link.
However you should also check with the manufacturer of the motherboard for OS compatibility.
I'm running a DG965MQ motherboard with my E6700...although a compatibility check beforehand was questionable this was the only motherboard accepting this chip with a MicoBTx form factor. I've been running it about a year (since the chip was released) with no problems at all, very happy the setup.