Hi Rick. Good to see you around.
I was a big fan of SHS6. Rock solid on my (recently deceased)XP system, and fine on my Vista machine.
As cwestmont noted, it it not entirely at home on the newer systems, and success seems to be hit and miss.
The X series had some well documented teething problems in X1 and X2, but X3 seems to be matured.
It is better suited to a W7/S8 environment than SHS6. I've only had X3 Studio for a few weeks, but I am liking it.
The interface is more flexible and functional. Some thing are not where you are used to them being, so there will be a bit of a learning curve.
To make it worthwhile, I would suggest at least the Studio version ($149 as an upgrade for you).
If I'm reading it right, you could upgrade to the Producer version for $399.
Here is a comparison chart for the different versions:
http://www.cakewalk.com/products/sonar/versions.aspxI went with Studio because it fit my budget and needs. So far, I am pleased with it.
Happy hunting.