the fonts used in your applications are generally all in a system folder located at CWINDOWS\Fonts (on a windows machine obviously...what OS arer you running?)
when placed in this global location any application can use them.
is the font in the word application on the same computer as the photoshop?
(each computer generally has different sets of fonts so the comp that you are working on may not have the same font that the client has in mind)
if not...what you need to do is take a copy of the font file from them and place it in the font folder on your comp and restart photoshop and it should appear in the fonts list.
a) i don't know what OS is
b) i don't have a 'windows' file on 'C' drive
c) i copied it to the fonts folder i have in the start menu. and it doesn't work, apparently
The best thing to do is search your system for the FONT folder, it'll be an icon that looks like a file folder, and copy the fonts in here. Then restart your computer, and everything should work fine. Otherwise, my only thought here is that these fonts are conflicting with others and that's the reason they won't work. START ---> SEARCH ---> type "FONT" ---> locate FONT file folder ---> open folder ---> copy fonts.