My own personal preference is Print Artist which comes with CD's and many of the templates you're likely to need.
However, this site:
http://greeting-card-software-review.toptenrev iews.com/
recommends Printmaster Platinum.
Version 16 of Printmaster Platinum is currently available from Amazon at �17.98 including postage at :
http://www.amazon.co.uk/exec/obidos/ASIN/B0002 C69ZQ/kelkoocpc-cs-software-software-21/ref=no sim
If I was starting from scratch with greeting's cards, I'd buy Printmaster Platinum as it would do all you're ever likely to need and a lot more besides. Click on the "reviews" button under the program name in the first link. A cheaper version called Printmaster Gold contains less templates, fonts etc.
On the other hand, if you type "greetings card designer software" into Google, a number of free programs are shown. However, in most cases, they're very basic.