You might want to start with this thread, then perhaps send a private message to some of the folks who commented.
It sounds like the Strange Eons software may give you some card templates, but I wouldn't really know. I just found this by searching "software" in the forums and quickly scanned the comments.
Quoting Eric Martin in that thread:
I don't exactly remember how I got the Arkham Horror stuff but I do remember that there was an option that allowed me to add it from one of the dropdown menus at the top of the page.
As for the cards, I can't really take much credit, since the program does about 90% of the formatting. My only input is the card text.