Still using Sonar XL 2.2

Hi Francis - Welcome to the forum! And I'm glad you recovered.

Studio Instruments should be fine with Sonar 2 XL. But they are VST instruments, so you will therefore need to use a third party DirectX to VST adapter program (Sonar 2 does not natively support VST). I don't think Cakewalk was including such an adapter until Sonar 3. Maybe it's available for download from the Cakewalk site.

The Studio Instruments are OK, not terrific. In general, you get what you pay for. I got them on sale for $30.00.

I personally think it would be worthwhile for you to update you software, even if not to the Producer Edition. There's a wealth of low priced and free VSTs out there, and you could benefit from a program that natively support VST effects and instruments.

For good drum loops, I recommend "Drums On Demand" (www.drumsondemand.com)  They're short audio loops, broken up into 1 or 2 measure phrases, and you just drag them into your song, mixing and matching however you like.  The thing that's particularly good about DOD (as opposed to some other loops I've played around with) is that they're clearly and sensibly labeled.  You don't have to go hunting through endless loops with meaningless names like "Loop1," "Loop2", etc.  Instead, they're sorted into folders based on tempo and style (example: Rock 120), and within each folder, the individual loops are named based on parts of songs that they work best in ("intro1" "pre-chorus" "bridge" "verse", etc, etc.)  Of course, you don't have to use them for those particular parts of the songs, but it's nice to have a guideline. 
DOD also makes a disc called "Essential Percussion," which I use a surprising amount.  It's a collection of useful loops of things like shakers, tambourines, castanets, etc.  Check out the demos on their site.

You can pay for an upgrade from any version of Sonar.  Sonar 8 Producer would cost you $249.00 plus you would get the new update for free (I think in a few weeks).

A lot has happened since Sonar 2, and you'll be able to keep yourself busy for a long time learning the new goodies. And there are lots of terrific instruments and effects.