I purchased Cakewalk Home Studio years ago and have upgraded many times.  I currently have Sonar X1 Producer.  I have purchased the X2 upgrade but haven't downloaded it yet.
 
My old computer has died and I have a new computer that I need to install Sonar on.  When I log in to my Cakewalk account, it gives me the option to download Sonar X1 Essential, Sonar X1 Producer, or Sonar X2 Producer.  Can I simply download X2 or do I need to first install X1, then install the X2 upgrade?  I suppose what I'm asking is whether the X2 upgrade I purchased will work if X1 is not present on the computer or whether the X2 download link will install the full version of the software. 

You can install X2 only if you wish. Each version of SONAR is complete. The "upgrade" refers to the price only. There were two items not included in X2 Producer that shipped with X1 Producer, Beatscape and Guitar Rig 4LE.
 
The sample content of Beatscape is included in X2 "Loops and One Shots". If you need the Beatscape synth, you will have to install it from X1. If you never used Beatscape, it might be a good idea to forget about it.
 
If you used Guitar Rig 4 LE , you can install it by performing an advanced install of X1. The advanced install will give you the option to select the parts to install. Select only Guitar Rig 4 LE to get the plug-in back.

OK, thanks for the prompt reply.  I've never used Beatscape, and I've used Guitar Rig sparingly, so will probably just opt for the X2 install. 

You are welcome. Don't forget to download and install the X2a patch after installing X2

Definitely.  The new PC has a 17" touchscreen so I am anxious to see how that works.

Are you running Windows 8?
 
You won't be able to use touch otherwise.