mixmkr
http://www.dell.com/us/p/inspiron-660/pd?oc=fddnrx508cm&model_id=inspiron-660
wouldn't this run X3 just fine and for $500. 12 gig memory, Win8 and 1 tb hard drive ?
No matter what computer you buy, you can break it with Sonar...load up 30 or 40 softsynths, have a prochannel with a few effects on each one, and then try tracking four live tracks at 32/96 over the top. While this is a silly suggestion, it exhibits a point. If you are a 'lone musician', laying down a half dozen softsynth tracks with some automation and 'humanization' and then recording 3-4 live tracks with a half dozen takes before mixing and mastering, then most modern mid-level or above computers will work for you. But if you are doing a movie score with orchestra (i.e. 50 voices), sound effects, 5.1 output, and lots of resampling and tempo management, then you might be well-apprised to get something a little more robust, because it will break.
The real key that I've found is that Sonar (and other programs like CAD, FEM, etc...) don't just let you know when they 'break'. They just get continually a little more flaky and less robust with more occasional crashes, a pop or click here and there, occasional "audio engine has stopped" messages, etc... Depending on how much you are willing to put up with this as your projects get more sophisticated vs. how much money you invest is a personal decision. You can also be completely anal about bouncing tracks to audio early in the creative process...this is a productivity choice.
denverdrummer
I've recently gone to using laptops over desktops. The power in most high end laptops is good enough for most everything I do, and add the portability, I need for working on other people's projects..........................
......................I'm a little unimpressed with some of the cases that are available. I feel many of them are way too big and clunky, even some of the mid tower stuff.
I'm addicted to having two large screens, and haven't found a particularly affordable laptop that supports it. For me the best deal is a solid desktop, and a modest laptop that I only use for live tracking and mixing.
Regarding the cases...it is worth spending a little extra money to get a good case with optimized cooling, speed-variable ultra-quiet fans, etc. There are some good choices out there in both rackmount (e.g. Athena Power) and compact desktop (Shuttle e.g.) configurations.