If it's just what's on the screen, the Snipping Tool is fine. If you need everything (including the stuff below what is visible), the the Snipping Tool can't do it. There are several screen capture apps that can do a scrolling capture. The best ones are not free.

My choice is FastStone Capture http://www.faststone.org/FSCaptureDetail.htm It has worked great for me in IE, Firefox and Chrome. The only thing I have ever ran into that it doesn't capture are Java based scroll boxes. And they are few and far between...

CaptureWizPro is another I have used that is quite good. Version 5 has an update to its scrolling capture component and claims to be able to capture nearly every type of window that scrolls. http://www.pixelmetrics.com/ My biggest beef with CWP is the price. $40 for it vs. $20 for FastStone Capture.

The old king of the hill was SnagIt http://www.techsmith.com/snagit.html But it's $50 and from what I've read, really doesn't offer enough extra features to make it worth that kind of money.