I have to agree with what has already been said, furthermore it seems ill conceived that your employers would not use a standard software of some sort to avoid confusion and incompatibility. However if you must encrypt your personal computer, there are many options. Regardless of what your employer prescribes for communication, you may want to encrypt your system to avoid liability or sharing of private data in case of theft or loss.
Just to be clear, the transfer of data IE. Emails, chats, file sharing, etc. if to be secure, must be the same across the network of users, your company would have to set up something all employees could use that is the same. Most email systems already support secure transfers, as do Facebook, Google, and AMHD, since the NSA scandal this is becoming commonplace; thus the http
s in the url and the padlock symbol that appears in many browsers. Furthermore, email through clients is usually secure through the use of SSL/TLS. I only propose that you encrypt locally stored files/emails/etc. if that would suit your needs.
Windows supports native encryption. Not that your system cannot be broken into, but it will use your login password to prevent anyone from seeing your personal files. If they capture your computer, the file names are still easily obtainable, however there content is obscured. A weak password is easily broken as well, windows native encryption requires strong passwords IE. A random set of numbers, letters, upper and lower case, and characters.
It is easy enough to do without the purchase of any software. If you open My Computer (xp), Computer (Vista/7), or This-PC (8), then open your Local Disk (usually the C:\ drive). You can encrypt any folder by simply right clicking on it and selecting "Properties" then choosing "Advanced" under the "File Attributes" section. You will see an option to encrypt the folders contents, check it and Choose "Ok", then "Apply" and "Ok". This may take some time to apply depending on the size of the folder. It would be wise to encrypt the "Users" folder in Vista and newer, and "My Documents" in XP and older. These along with any programs that store data in their own directory should be encrypted. This will cover any email received locally, or other user data/files that are on your computer. You may also choose to encrypt other folders if you have data stored there. Also in this case it would be wise to turn off any network shares you may have enabled.
On a Mac you can use
FileVault to encrypt your entire drive securing all files.
Both of these are NIST FIPS Compliant.
Bitlocker is also an excellent tool that comes with Windows, however it is only on Vista and newer, and does not come with certain editions. See
here for overview, and
here for simple instructions.
Normally I would also recommend
TrueCrypt, however as their support ended, its usage has become quite controversial in the security world. You may also consider
Symmantec PGP or their free version, activated after the trial-ware expires.
Here is a large list of security software that is fips 140-1 compliant. A great deal of it may be useless to you.
Some computers allow hardware level encryption accessible through the computer's' BIOS or certain pre-installed utilities. See your computer's manual.