I have a number of customer who have asked me this, so i thought i would blog it in case anyone else wanted to know.
If you want to create top level sites in the root of one of your WSS Virtual Servers E.g. /TopLevelSite1">http://<servername>/TopLevelSite1, /TopLevelSite2">http://<servername>/TopLevelSite2 etc... here are the steps you need to follow:
Starting with an un-extended virtual server.
Extend the virtual server using the STSAdm.exe tool using the -donotcreatesite switch.
E.g. stsadm -o extendvs -url http://servername –donotcreatesite
This will extend the virtual server and not create a root top level site. This is really important.
Go into the configuration settings for the newly extended virtual server in the central administration pages. Go into Managed Paths and add '/' as a managed path.
Now you can go back into the central administration pages and create a new top level site under the path '/'.
The key to all this is to extend the VS using the STSAdm tool ... not the central administration pages. You dont get the choice of not creating the root site when you extend if you use the HTML admin pages ... and that will stop you from adding the '/' root managed path.