BeOS is a fast stable and easy to used operating system.  In many aspects it is very similar to the Mac OS, but it also has many similarities to Linux.  there is very little support for hardware, and there are a limited number of applications available for it.  It is merely a toy, I suppose if you really wanted to you could use it a your primary OS but I think Linux would be a far better choice.  I have not been able to get Be working with my @home cable internet, whereas QNX and Linux are both very easy to get working.