Microsoft Office documents often include data that can compromise your privacy or that you don't want others to see, such as hidden text or cells, document revision history, names of document authors and reviewers, and so on. When you send someone a document, they can easily see that information by viewing the version history and the document's properties, and in other ways.
It can be time-consuming and impractical to remember to review every document you send out via e-mail to make sure it doesn't contain privacy-compromising information. Instead, get Unedged Software's SendShield.
Whenever you send PowerPoint, Excel or Word documents via Outlook, it examines them to see if they have any of private information. It then details what it finds and lets you remove the information with a single click. It deletes the information only from the copy of the file you send via e-mail, not the original on your hard disk.
You can also have the documents turned into PDFs and sent that way instead of as Office documents.
SendShield is in beta, and for now is free. However, when it gets out of beta, there is a chance that it will become for-pay software. (The company provided no details on timing or pricing.)
Many for-pay antivirus programs, such as Symantec's Norton AntiVirus, are system hogs, taking up far too much RAM and system resources, which slows down your PC unnecessarily. Not only that, but you have to pay an annual fee for using them.
There's a better way: Get the Avast Antivirus software from ALWIL Software. It's lightweight and takes up barely any RAM or system resources, it's simple to use, and it'll do everything you need by providing live, resident protection as well as scanning.
The software uses a shield metaphor for its multiple types of protection. There's an antivirus shield, one that protects against Web-based threats, another for e-mail protection and so on. You can customize the sensitivity of each shield.
Avast includes automated updates of virus definitions. The independent testing site AV-comparatives.org rates its effectiveness as Advanced+, the top level. I've been using the program for well over a year and a half, and it's caught every threat that's come my way.
Note that Avast is free for home use, but requires payment for business use.