You might need to check them in a text editor to make sure the version number is 4.03 (second line of the file) but apart from that they should work just fine. Oh yeah don't forget Poser4 uses rsr files so you might have to use a convertor on them http://www.senosoft.com p3do explorer with the rsr plugin is my favourite tool for the job :)

Windows 7 64Bit
Poser Pro 2010 SR1