Just bought and downloaded X2 Producer. I'm currently running X1
 
Quad core i5 8 GB ram Win7 64bit
 
two internal hard drives and two external
 
What is the best way to install and in what locations should I put the various parts of Sonar?

I have always done a more or less default install. The only thing do is check that all 64 bit plugins are also installed. 
 
I don't see a problem with putting the Dim Pro samples and SD 3 samples on the C drive. though I have all my other samples for NI on a D drive as well as GPO. project are on the E drive. 

I just did the same update you're doing.  I've always put everything for Sonar on the C Drive.  All my samples for instruments go on a drive (Dimension, Stylus, etc).  Sonar projects and wave data are on a third drive.

Doncolga, did you uninstall X1, install in addition too or is the X1 install "upgradeable" to X2 . . . ?

Doncolga, did you uninstall X1, install in addition too or is the X1 install "upgradeable" to X2 . . . ?

Doncolga, did you uninstall X1, install in addition too or is the X1 install "upgradeable" to X2 . . . ?

Doncolga, did you uninstall X1, install in addition too or is the X1 install "upgradeable" to X2 . . . ?

Doncolga, did you uninstall X1, install in addition too or is the X1 install "upgradeable" to X2 . . . ?

Doncolga, did you uninstall X1, install in addition too or is the X1 install "upgradeable" to X2 . . . ?

Sorry about the post clones . . . only hit Submit once, got an odd error popup and the page crashed. When I reloaded it I saw the multiple posts and I don't see a Delete button or function . . .