USBCrypt is the "on-the-fly" encryption software, that works by creating a Virtual Encrypted Disk on the host drive and protecting it with the password of your choosing. You decide how large the Virtual Encrypted Disk should be: it can take all of the available space of the host disk, or only a fraction of it.
After you encrypt a drive with USBCrypt, you can enter your password to start the Virtual Encrypted Disk and use it just like any other real disk: you can browse it with Windows Explorer or any other software you have, copy files to it, or move them back to your main hard disk, save documents to the Virtual Encrypted disk and open them when needed, and so on. Any file that you move to the Virtual Encrypted Disk gets encrypted transparently, without you having to do anything special. When you open a document or move a file out of the Virtual Encrypted Disk, it gets decrypted automatically on the fly. When you no longer need to work with the private files, you can stop the Virtual Encrypted Disk and it will become locked with your password again.
USBCrypt puts its software on the encrypted drive, too, to make you able to use the removable drive on other computers, without USBCrypt installed on them. For example, if you've purchased USBCrypt for use in your office, you can take the encrypted USB drive home with you and use it on your home computer without installing the full copy of USBCrypt software on your home computer.
From Windows XP to Windows 7 and 8, both 32- and 64-bit, with the latest service packs and hotfixes, all are supported by USBCrypt..
USBCrypt - 64bit software