Sorry for the slow reply, (shhh, I'm suppose to be working) but what qpid said is correct. For about 98% all applications software RAID is all you need. Only in an application such as a movie house, or for scientific research, or other applications with high levels of data being stored does a hardware RAID become necessary.but does the MacPro comes with raid anyways?
Indeed!If the OP needs external storage, then he can go the eSATA RAID route, which is MUCH cheaper than the Apple RAID route.
Remember, eSATA can do 3.0Gbps, which is about 375MB/sec....and if you have a 5 Drive setup at RAID0, you can easily achieve this.