There are a few options:
1 - do you want to stop others using the PC? If so, set a BIOS password.
2 - try something like this: click here
"If you are worried that someone might have access to your documents, emails, sales projections, contracts, tax returns or receipts, romantic letters, or any other private files, then this product is for you.
Don't rely on the simple password protection mechanisms of popular Office packages, or compression utilities, they can be broken or by-passed easily.
Get your self state-of-the art encryption, for this task you need either this product, or something like PGP. PGP is great for encrypting email's, but when it comes down to it, for file encryption it's cumbersome, each time you need to use a file you must decrypt it, update or print it, then encrypt the file again, remembering to wipe the original.
In addition how do you name your files? Do you use descriptive files such as bank-statements.zip.pgp, xyz-corp-contract.doc.pgp, or whatever, these descriptive filenames give others information you would rather they not know. Did you know that a certain Office package keeps a record of the last X files accessed in the registry even if you turn this feature off in it's user interface?
E4M solves many of these problems. It's fast, seamless, integrated, legal, free, 128-bit encryption regardless of who you are and where you live.
E4M is an on-the-fly disk encryption product. What this means is create a volume on your hard disk, CDROM, floppy or other media which is essentially just a normal file. The file however is in fact a file system itself. It contains all the structures needed by your operating system to recognise the file as a file system of a particular type such as FAT or NTFS. This is called a "file hosted volume".
Or you could choose a blank or unwanted partition on a local hard disk or floppy disks and format it using E4M. You can then mount this new encrypted volume, and use it like you would any other drive. This is called a "Raw partition volume".
The only difference is that Raw partition volumes do not have a file system in the middle, so they provide an encrypted file system on top of a Raw partition. As opposed to file hosted volumes which need an existing file system to "host" the volume file. An example would be a E4M volume called "myfiles.vol" located on the C drive, rather than the same volume located on the second partition of your hard disk.
To your operating system, these new volumes will work exactly like your C drive, or any other drive on your system.
Tools are provided to "mount" a volume, and to create a volume. The process of mounting a volume involves pretending that the volume file or partition is in fact a removable media device attached to your system.
Thanks for using my product, and enjoy!
Paul Le Roux."