It's sometimes useful to have both Sametime and Quickplace running on a single box. It's not supported...but so what, just use it for your own edification.
This will get Instant Messaging and awareness working - online meetings are another matter.
Anywhere you add the hostname of the server please use the fully qualified domain name (fqdn), such as "domino.domain.com" - otherwise this will not work.
The versions are Win2k, Domino 7.0.1, Quickplace 7 and Sametime 7.5.
The installation order of the software is essential. Don't install Quickplace last.
Install Domino first, then Quickplace. When installing quickplace you will be asked for an admin username - I used qpadmin. The qpadmin user does not need to exist in the Domino directory. Once the server has started log into quickplace as the qpadmin user and set the directory type to Domino, then add an existing Domino user account as an additional Quickplace administrator.
In Notes, open the server document and set the "Session Authentication" to Multi Server (SSO). Then restart the http task.
Log into quickplace as the Domino user you just added and check that all appears fine.
Stop Domino and install Sametime with the option of using Domino as it's directry.
Start Domino and log into Sametime via a browser using the existing domino acount that you set to be the Quickplace administrator and check that it appears to behave properly.
Browse to Quickplace and edit -> "Server Settings" -> "Other Options" to contain the (fqdn)hostname of the server for both "Sametime Community Server" and "Sametime Meeting Server".
It's not neccessary - but I restarted Domino at this point.
Log into Quickplace as your Domino user and you should now see Sametime awareness anywhere your name appears.