Ok, first, just to cover the basics, Quit any running applications. Actual quit, not just close. New fonts don't show until the app is reloaded. Moving on...
I'll rarely suggest using
FontBook (/Applications/)...but this is a good time. It'll browse all installed fonts on your Mac.
If that doesn't work, then try using a font previewer like
Font Sampler. It will let you view uninstalled fonts on your Mac. If they show, then check to make sure they're in
Users/[your name]/Library/Fonts
If they don't show, you may have bad fonts.
Short version: those font formats work in OS X. There is no code difference for Win of Mac
since OS X. I would invesigate where you got these fonts from if they're giving you that much trouble.
Google will help you find sooooo many free fonts that are identical to the ones you're using most likely (just search for "Free fonts
'name of font'")
Good luck.