A new version thing for x64 bit computers (Vista, Win7, Win8) was put on VPVP, but the link isn't right.
(file:///M:/Programs/MMD739d_x64/temp/HP/pict/MikuMikuDance_v739x64.zip That's the original link)
So if you had problems download it too, like me, then please use this one, cause it works.
http://www.geocities.jp/higuchuu4/pict/MikuMikuDance_v739x64.zip
^ The MMD
You also need to install
http://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=14632
and
http://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=35
I hope I helped. ;w;