Let me phrase this another way.  A newbie has no reason to use (or even need) RAID.  Striping is ok but with today's large disk sizes is more of a fad than a necessity.  
If you want a processor to cut down on cpu use for RAID 0 you are sadly mistaken.  The processor is for true RAID at levels higher than 5.  A processor is NOT needed for striping.  This is why you can have a very simple controller doing mirroring and striping.  Additionally, when you tie more than two drives together, the performance does NOT increase in a linear fashion as it does when going from one drive to a striped pair.
Unless you absolutely need >50 MB/S write speed (99% of the users do NOT, even for NLE) there is no need for more than two drives.
Processor use.  This is the biggest and most debated topic.  It's also the most misrepresented metric (second to access times) out there.  CPU Utilisation is USELESS on its own!  Why?  In order to be accurate, the program MUST tell you the data rate it used to determine the CPU Utilisation.  Please stop using programs like HD Tach and especially SiSoft!  I'd recommend Winbench and even IOMeter.  They take long to run, but at least you'll have an idea of what your system is actually doing!  Ask Eugene over at 
The Storage Review Website what he thinks of HD Tach and SiSoft! 
Regarding 3Ware products; did you know they have an EIGHT channel controller?  Getting 8 disks connected to that would most definitely present a challenge because of the cable length!
Cheers!