You might also want to go out and download "CCleaner" and/or "EasyCleaner", which are freeware registry cleaning tools that will go in and root out any FUBAR entries that might be preventing your install of Poser from starting.  All it takes is one wayward registry entry to take what used to be a working program and turn in into a virtual potato. 

And yes- I had Posr 7 and D/S installed and had also uninstalled the latter, with no ill effects.  And I had uninstalled D/S mostly because I couldn't stand the interface.  The one used in Poser isn't the best at times either, but DAZ took a step backward with their GUI as of late.