You can absolutely use Sonar to make beats. DJ Johnny Juice is a member of these forums and has been using Sonar for the past several Public Enemy records. You can read an interview here to hear some of what he has to say:
http://www.cakewalk.com/Artist/PublicEnemy.asp Sonar is what is called a "sequencing program," and is comperable to other sequencers such as Logic, ProTools, Cubase, or Nuendo. These programs pretty much give a full-blown recording-studio-in-a-box. Somewhat confusingly, products like Project5 and Reason are called "software studios." They are a different beast, designed more specifically for generating sounds and loops entirely within the computer. Their recording, mixing, and editing capabilities are usually much more limited, and the user interface is focused on creating sounds and loops on the computer.
Sonar has a lot of capabilities and flexibility that things like Reason and Project5 do not have. They are both excellent programs, but they don't "do" anything that can't be done in Sonar. Sonar will pretty much allow you to do anything you could do in a commercial recording studio. The downside for a beginner is that it includes virtual versions of all those millions of knobs, faders, patchbays, and blinking lights and it can be intimidating if you're new to professional audio.
Before you give up on Sonar I would suggest you set aside an afternoon to check out the included tutorials and work your way through them. There are also a ton of tech tips posted on cakewalk's web site that may give you some ideas. Sonar comes with a host of tools that can be used for creating loops and beats, and there are tons of plugin effects and tools that can be got for free or cheap that will expand it's capabilities even more.
If you decide to keep looking for different software, then before you go spending any more money I strongly suggest you check out the demos-- every software company allows you to try their product out for free before you buy it. I am pretty sure the frustrations you're having have to do with what is commonly called "workflow." Certain kinds of software are particularly well-suited to doing certain things, and the demos will give you a good idea of how well a particular piece of kits flows with what you're trying to accomplish. And bear in mind that you can use products like Rason and Project5 within Sonar, so you could use them to create beats, loops, and simple arrangements and then feed them to Sonar and use Sonar as mixing, editing, and mastering environment.
FWIW, Products like Cakewalk Home Studio and Cubase LE are basically cheaper, stripped-down versions of Sonar. They might be slightly easier to work with just because they have fewer features, but they are not particularly better-suited for creating beats. If you are having a hard time working with Sonar and feel like it's getting in the way of your creativity, then you should probably check out one of the above-mentioned "soft studios."
Cheers, and best of luck.