How can I install wildcard SSL cert from GoDaddy?

I have a GoDaddy wildcard SSL cert that I am trying to install for use with PRTG. I have the following files from GoDaddy:

cert.p7b cert.cer cert.pfx

I have gone through several walk-throughs, but still get stuck when trying to create the necessary files for the cert directory for PRTG (.crt, .key and .pem). When I thought I had it, I replaced the files (after backing up the originals) and then attempted to restart the core service, but the service kept stopping. When I checked the windows event logs, I got the following:

"Could not start webserver: Tried to start Web server for configured IP/port Settings:Could not load key, check password. Tried to start web server for IP 0.0.0.0 and port 80/443(SSL) - Failed: Could not load key, check password. ID: -1000"

Is there anyone, knowing the files I have from GoDaddy.com, that could help me through this process?

Thanks!