The older stand alone extensions cannot be installed at the same time as data bridge.
Data Bridge is a replacement to those extensions, that is why they cannot be installed together, they cause conflicts.
there are a couple workarounds:
1) Have a previous version of dreamweaver installed, for example, install both DW CS4 and DW CS 3.
install the previous version in DW CS3 and the Data Bridge in DW CS4
2) Create another user in the operating system
under one user, install the previous versions, under the regular user install Data Bridge