Went on a drive with a mechanic and he did a load test on the clutch and he says that my clutch is going. I could tell that my clutch was weak because of the difficulty I have in engaging it smoothly, but I have been driving manual for years and never felt clutch slip like I am experiencing while the clutch is fully engaged.
However, while looking around on the internet I found this little nugget on eHow.com: "Chattering is another common problem. This is a jerking and and grabbing action that occurs when the clutch is engaged." This seems to pretty accurately describe the problems we are having with our cars.