Wirite protect files and dirs

[Rksk]

Is there any best way to add protection to files and dirs in windows?

( like kaspersky program files' protection )

[Neo]

I normally use RAR with password protection where I can browse folders and files just as in explorer.

[Rksk]

But it isn't suitable for data files of a software?

[Neo]

do you mean files that are required to run your current software? If so, we are unable to have a perfect file protection as encrypted files can't be identified by the software. In that case, you will only be able to hide the folder (there are some advance hiding software). However these files can be viewed if we use a sector level editor like WinHex.

Encryption is the perfect way to protect files. However after encryption, you'll not be able to use them without decrypting.

Other than these, I don't see any problem in encrypting data files.

[Rksk]

My goal is protect exe,dll,... files from PE modifiying viruses.

[Neo]

There are many if you just google.

This one is free.
LockAnEXE

These are shareware.
EXE Stealth 3.15
GiliSoft File Lock
Exe Guarder
Exe Wrapper
Akala EXE Lock

I use PE Explorer when I need to reverse engineer EXE, DLL, COM, etc... You might be interested with that as well.