[17MBPC2D]

I've researching as what encryption program is Best to purchase...Knox? PGP? Any suggestions?
Requirement is that encryption program must be both PC/Mac usable....simultaneously as I have both PC/MAC accessing the data.

[clesch]

depending on what kind of encryption you are looking for, truecrypt might be what you are looking for.

//edit: i just saw that the Mac OS X version is still in development, so scrap that suggestion. sorry.

[ghporter]

PGP has been standardized; it should work seamlessly on both platforms. Further the Gnu version, GPG (Gnu Privacy Guard) is both available and free.

[mitchell_pgh]

doesn't zip have some such encryption?

Not sure...

[besson3c]

Gnupg. The free standard of PGP.