I do NOT recommend importing all of your windows fonts to Linux. Sure, you paid for windows, and should be able to use all the windows fonts on any OS you want, but Microsoft (and their lawyers) may not feel the same way. Read your license agreement carefully. Instead, you should install the freely released and  licensed to all for any use Microsoft "core" fonts. (Also, Arial-9 killed my firefox install)

But, if after that warning you still want to import all of your Microsoft Windows truetype fonts from your windows partition to your linux partition and install them system wide, here is what to do:

Gain root privileges: sudo bash

Make a directory to store the fonts: mkdir  /usr/share/fonts/truetype/msfonts

Find the fonts on your windows partition, for me this was /media/sda1/Windows/Fonts

copy the fonts over: cp /media/sda1/Windows/Fonts/*.ttf  /usr/share/fonts/truetype/msfonts 

Re-create the font cache:   fc-cache -f -v