We used to use snagit within the company but when we started moving to Win7 the PTB decided that the built-in snipping tool was adequate and stopped purchasing the licenses for snagit. I tried snipping tool but didn't find it as user-friendly as snagit so went looking for a freeware alternative and came across Greenshot - it's great. It doesn't give me quite as much funcitonality as snagit did, but for a freeware piece of software it's versatile enough, prempts the print screen key (unlike snipping tool) and allows me to mark up the screenshots once I'm done, which is exactly what I was looking for. Best of all, it's free even for commercial use!