fonts and OS X

While I am waiting for my new ibook to arrive I have begun thinking about my transition from my PC to my new mac.

Anyway, How do I deal with fonts in OS X? I have heard that you can use true type fonts in OS X, which I don't know is true or not. But my main concern is opentype fonts. I am under the impression that opentype fonts will work on pc(which they do very well), and macs. I was on a friends g4 with X.1.4 and I tried placing an opentype font in their font folder, but I was not able to access the font.

Is there a way to have these fonts work? Also, which font management program do you recommend for OS X.

Thanks in advance.

I should add that the opentype font I tried to install was called "aachen.otf" and it was not recognized.

I just grabbed the first A font that I had

Thanks

I will have to give suitcase a try, but I am still not able to install my opentype fonts by copying them into the font folder.

Hopefully suitcase will work.