Sorry for the delay in responding.
There is no default username and password. When you first install ACS you connect to the web GUI on the same machine that you installed it on, this doesn't ask you for a password. From there you can go under the Admin section and add a username/password, which you can then use to browse to it from another machine.
Keep in mind though the ACS 3.2 is NOT supported on a Win2003 machine, so whether you browse to it from another machine or not, if you run into issues you will be very limited in the support you get from Cisco.
The release notes for ACS 3.2 (detailing the supported versions) are here:
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_soft/csacs4nt/acs32/rn322.htm#wp1039706