There is a version that will run under NT, but don't expect stellar performance of postgresql under anything but unix.
If you've got a spare of box (like th $199 Pentium 100/64Meg Ram boxes you see at closeouts) you can built a nice stable reliable db server with little or no knowledge of Linux or BSD to get it up and running. Heck, RedHat 7.0 can install the whole database and have it mostly setup for you and ready to go with just a few selected items in teh setup screen.