A pea sized amount is really too much. If you're concerned that you may have used too little, you can remove your heatsink and see what the coverage looks like. If the entire CPU appears covered, you used plenty (you'll need to clean it and reapply a fresh quantity of thermal grease after doing this - don't just put the heatsink back on). What kind of temps are you seeing, what CPU is it, and what heatsink?
phenom II 955 OCed to 3.8. Using Intelburntest for a few rounds, it got up to 55 pretty quickly, and I think it idles around 37. Can't remember exactly what the heatsink is called, but it's a gemini II or something like that. My case wasn't big enough for a 212+. Also, I'm using thermaltake tg-1, so that's why I was really hoping for lower temps, considering I paid almost 20 bucks for just the grease.