One would think that a true professional would not embellish their resume. However, we live in a society where you can get away with certain fabrications for a while (cf Madoff, Enron). In regards to the resume, the truth will come to light when that employee is face to face in the interview. For example:

"Substantially increased security and performance of systems by implementing new anti-virus software and critical system updates."

1. How did you implement the updates during your busy daily schedule?
2. What technologies did you use to help facilitate this implementation?
3. You mentioned "substantially" in reference to critical updates, please elaborate on the situation you had and how did you solve it?

By asking these challenging questions to the accomplishments, you can be certain the candidate is telling the truth. Of course, there are people who can manipulate a conversation, but that's where your interviewing skills have to be better than theirs.

I agree with mckinnej about keeping a log of my accomplishments - it is important to remember what you brought to a company, even if it is an increase in customer service. Keep all letters of references, and make sure you keep your references updated; it is quite embarrassing to have a potential employer call a reference to find out they are no longer there. Make sure you get qualified email addresses and telephone numbers from the references; don't have an employer call them at their home unless it is okay.

To link my point to this article: have references that can support the accomplishments you had at the company.