I do have P6, that's my first 3D program, but it's on a 32bit WinXP machine.  P9 or P10 would be good matches for Win7.  Using old software on a new OS, or new software on an old OS, you can expect problems.  So, I would consider it pointless to update to P7 (and probably even P8).  P9 or P10 will exploit all your CPU cores while rendering, whereas P6 did one bucket at a time (single thread).

     I began in P6.  I would consider P9 or P10 to be as easy to use, with the added benefits of multiple libraries any old where (except not in program files), a much better morph tool, SubSurface Scattering, and InDirect Lighting.  If you get the pro version, you can network render animations (use your old/secondary computer to help your primary).  We have a fitting room now.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5