guitar track upgraded to GT Pro 4 help please

 
Hi there Scott, welcome to the forum.
 

I'm new user of V 20 studio I upgraded Guitar Tracks to Guitar Tracks Pro 4 WHat do I do with the old version that's also on my computer

 
Just leave Guitar Tracks on your computer and continue to use Guitar Tracks Pro. If you uninstall the older version, you may lose some or all of its features which Pro can use. In other words, any projects you started in GT4 will open and run fine in GTPro4 but any effect or process that is unique to GT4 will not be available in Pro if you no longer have the older version on your computer.
 

...can I use the audio content of GT with GT Pro4 or do I have to use the GT (old) to use the audio files that came with it?

 
Yes, in GTPro4 you will be able to navigate to the folder GT4 created to store the audio samples. You should also be able to set GT4Pro (in Options > Folders) so it opens this folder as default for importing these files.
 

...especially the song files

 
Yes, GTPro4 will be able to open both project files (.cwp) and bundle files (.cwb) created by GT4.
 
Hope that helps Scott, if you need any more information, just ask away.
 
 
Steve