www.paypal.com/gatewayupdate
 
"Important update for Payflow Pro and Website Payments Pro Payflow Edition customers
 
We’ve added new security features to our Payflow gateway service that will make your payment processing even safer. Because of these new features, you must update the Payflow code that’s integrated into your web site. All merchants should update to Payflow Pro Software Development Kit (SDK) version 4.3 or higher, or use our direct HTTPS Interface.
 
On September 1, 2009, we’ll stop supporting older integrations. To continue processing payments, please make plans to update your Payflow integration as soon as possible. "

I sent this question to support and will update with the answer.

The reply is that ViArt does not use SDK so this update won't affect us. (SDK must be an old technology... my old cart was using it and had to update.)

Hmmm... just noticed this in the setup for Payflow Pro...
 
"First of all you need to download the Payflow Pro SDK and extract the files to one of your server directory.
 
Set PayFlow SDK parameters in the parameters list below
Binary - absolute path to PayFlow executable module pfpro or pfpro.exe
Library - absolute path to PayFlow library
CertPath - absolute path to the folder with certificates
 
Then please specify your login information like 'VENDOR', 'PARTNER', 'USER' and 'PWD' in the fields below."
 
Looks like I need to contact them again.

Okay, the problem was that I was looking at the "Verisign Payflow Pro" option (#23) and the most recent version of Payflow Pro is #50... "Payflow Pro Direct". That is the one to use.