It is always tough to fire an employee, no matter how much s/he deserves it.  But, speaking for the employee, it is can be much more difficult if the employer employs little or no finesse.  When to terminate employment is a big part of the equation.  Michael Maslanka gives some excellent advice, suggesting earlier in the week is better.  Over the years, I have heard from many employees, "I would have let it go, but then they did X to me."  What they mean is that often, they suffered some pretty clear discrimination or violation of some contractual right.  But, the employee did not become angry enough to see me or someone like me until the employer did something that was pretty insensitive.   A common tactic is to fire the employee on the spot and escort him/her out of the office.  That is huge.  That is when employees go see a lawyer.  

I appreciate the need to secure computers, files, etc., but employers should consider very carefully when they find it necessary to embarrass a worker in front of her co-workers.  I have some friends who run a chain of mom and pop sandwich shops.  They are very smart.  They do not have college degrees.  But, they understand this well.  They always fire someone with two weeks notice, unless a clear case of theft or its equivalent is involved.  Be firm, be tough, but do not embarrass……