AOLserver 3.3+ad13 is the best bet if you do not want memory leaks.
Nsvhr does not seem to work with it though.
OpenACS 3.2.5 does not require nsxml so unless you need it for something else you do not have to install it.
You need the Postgres driver from OpenACS.org.
I don't use RPM so I cannot recommend if you should use them or not.