Well, my data HD failed two weeks ago, and a replacement is on the way.  I'm also thinking I'd like to replace my boot drive with the SSD I bought some time ago.  At some pont though, I expect to have the SSD drive and my current drive installed at the same time.  What I'm wondering is, assuming I can authenticate the new install on the SSD drive, will the current boot partition remain authentic?  Is it possible to have two authentic installs of Win7 on two different drives within the same computer?

One drive is a boot, the other would be identified as a slave.  There shouldn't be any conflict AFAIK.  I've reimaged OS from one drive to a larger drive and authenticated the new drive without any problems; the other drive would be reset as a slave and will not be involved in the boot setup.

It is techicallly a violation of the license to boot one license from 2 partitions.

HOWEVER...

There should be no problem at all if it is an auto validating OEM copy.  I would't think it would be a problem otherwise provided you are cloning the original partition, if you are simply keeping the original drive as a backup in case the SSD fails.  If you were booting from different paritions often ii might raise a flag.  If you install it from scratch it creates a unique product key; I think you could copy the validation files to the new partition, but you are on your own as far as that goes...