Free to try : Folder Crypt

From LittleLite Software: With Folder Crypt you can password protect any Windows file or folder using low level encryption and standard algorithms, such as DES, Rijndael and Blowfish with keys up to 2048 bits. The program performs a true bit per bit encryption of your data. Original files and folders may be shredded. The encryption process is not reversible. Easy to use with its improved shell integration. Full international characters support. Version 3.1.4586 enhances compatibility with 64-bit systems, includes new archiving algorithm, better memory handling, and removes 2GB limit. Download : http://www.zdnetasia.com/downloads/pc/swinfo/0,39043052,39232916s,00.htm