If you’ve spent any time at all learning about web design, online marketing, or conversion-rate optimization, you’ll have heard to never put calls to action below the fold.
Interesting bit of UX from KISSmetrics. The notion of "The Fold" needs updating, if not deleting altogether.
"The issue isn’t whether the call to action is visible when your prospect first arrives. The issue is whether your call to action is visible at the point where your prospect has become convinced to take action."
In spite of everything, people will still read top to bottom, and (usually) left to right, so the CTA needs to be placed in the right place for that page. Cliches like "above the fold" really do very little to help.