Transferring Photos

I have a MacBook Pro - about 2 years old.
I'm trying to transfer some of my photos and video clips onto a flash drive or other portable drive. I tried exporting some of my albums while in IPhoto. I tried dragging files to desktop or to a flash. Nothing seems to work.
What is the best way to transfer files? I want the original, full size version. I want to be able to plug the flash into a PC and use the files there.
Please help.
Thanks very much.

Can you explain the process you're going through? Any error messages etc?

Possibly the Flash Drive is formatted NTFS. If so, the Mac cannot natively write to it. Will need to format to FAT32 or get a 3rd Party NTFS driver such as Paragon Software's offering.