I am about to install X3 on a new computer. I really want to put all samples/Dimension Pro over on another drive and just install Sonar on C: drive.
 
Is there a best way to do this? Do I just need to look for the Drive prompts?
 
Thoughts?

Watching for the prompts works. If you don't want to bother with it, miss one or find something else you want to relocate use mklink at the command prompt. Personally, I would use mklink after the default install. For example, to relocate the DimPro Mutlisamples from the default location to e:\Samples\DimPro the process would be:
1) Move "C:\Program Files\Cakewalk\Dimension Pro\Multisamples" to "E:\Samples\DimPro"
2) Run cmd.exe
3) At the command prompt type:
   mklink /j "C:\Program Files\Cakewalk\Dimension Pro\Multisamples" "E:\Samples\DimPro"
If you prefer, you can go with registry edits but mklink is more convenient and works when the add on library installers fail to pick up the custom registry changes (whether made during the original installation or after installation). All the information about the registry entries is here http://forum.cakewalk.com/FindPost/2673527

Interesting - thanks for the tip.