FYI, I couldn't get the 64 bit version (from here http://labs.northscale.com/memcached-packages/) to install as a service until I ran memcached as administrator.
I just went to the executable's properties, then the Compatibility tab, and checked "Run this program as an administrator" (There a ton of other ways to do this, but it seemed simplest)
Then I was finally able to successfully run: memcached -d install
Don't forget to start the service after it is installed too :)