I finally got my MicroSD card today. Popped it into my last cellular phone (SAMSUNG SGH-D807), transfered all the files to the card, ejected the card, inserted the card into my BB 8100. To my disappointment none of the files are showing up in their respected folders. The "Media Card" folders all seem to be empty. I hooked my BB to the computer and the Media Manager shows that all the files are there. Pictures are in the Images folder, Music in the music folder. I tried popping the MicroSD into other devices (i.e. tv, digital camera, other phones) and they all read my files. Why isn't my BB reading the files on my MicroSD card?

What formats are the files and are they under the blackberry folder in the correct directory?

Welcome to the forums.

Copy all the files to your PC. Then format the media card using the BB. Go to Options >Advanced Options >Media Card. Hit the menu key and select "Format Card."

Then transfer the files back to the card.

.mp3, .jpg

from what I understand they are compatible with the 8100.

This is a brand new card, should I still try format it?

Yes please do what was suggested and let us know.

Yep, you need to format the card in the BB.

Don't I feel like an idiot. I was in the process of backing up all my files as John Clark suggested and I noticed something in the directory. It basically looked like this:
Apparently I had all the files stored in the Images/Videos folder and not the respective BlackBerry folder. Doh! Sorry for wasting everyone's time, but thanks for the help!

I'm new to the BlackBerry cult and hope to learn a lot and eventually contribute back. Thanks guys!

I still recommend reformatting the card in the BB to prevent future issues. Save yourself the future trouble.

Will do, better now than later. Thanks!