I have an Axim X51v, and I am having problems with a few of the programs I use on my PDA. The installers for programs I use (epocrates, mobile merck medicus, pocketbreeze) all are set to use Activesync and therefore do not install to my PDA. Can Activesync be used with Vista? If not, does anybody know of a way to get these programs to sync to my PDA in Vista?

No, you cannot use Activesync with Vista. I would assume the only solution is to send an email to the companies that write the respective software and ask when they plan on supporting Vista or let them know that they need to support it because customers are "eager" for the updates.