I always have a version of Poser 7 installed (usually Poser Pro) to assure that my cloth are compatible with as many as possible. There is no problem running the old Poser Pro together with Poser Pro 2012 on windows 7 or 8 at the same time. That goes for both the 32 bit and 64 bit versions. It can be helpful to have both versions alongside to solve some problem. Another reason for have an old version of Poser lying around is that many products no longer function in 2012 such as for instance PhilC's BVH_helper.