PostgreSQL 8.0 Beta has been released. The exciting thing about this release is native Win32 support. That's right, PostgreSQL will run as a WinNT/XP Service and you don't need any special libraries, or configuration. All you have to do is double-click and install.

http://developer.postgresql.org/beta.php

Windows install is here: http://pgfoundry.org/projects/pginstaller

IMO, MySQL has been so popular among developers in part because it was available for Win32. It's easy to setup and use your local Windows machine as a development platform, instead of setting up a *NIX server just for a development database.