Be careful with Western Digital and RAID. WD drives no longer allow you to use the wdtler utility to turn TLER off for a RAID configuration. This means you need to buy their RAID approved disks for a substantial premium. I haven't tried, but I believe the regular drives would be completely unstable for RAID 0.
I use a set of 4x1TB Caviar Black REGULAR disks with the ICH10R controller in what Intel calls RAID 10, but I think is actually RAID 01. Every two to three weeks, the TLER causes my controller to boot one of my disks from the array. It's never the same disk, and when it happens, the entire system crashes, and I have to hit the big blue button to reboot. From BIOS, I then have to enter the controller, which always says that two disks have failed, and the system isn't boot-able- do I want to fix it? Well, of course I don't want to fix it... I just want to throw it out the window, and do all my writing with pen and paper from now on. So I hit Y, and magically one of the bricked disks is OK, and the other (of the two failed) will still be labeled broken, but the system is now labeled as boot-able with three good disks. I then have to select the broken disk, remove it from the array- which fixes the disk- tell the controller to include the now fixed disk back into the array, and reboot. At that point, everything loads normally, and once in Windows, the broken disk has data written to it again, and the array is made whole in about 5 hours time. With RAID 0, you would have to restore your OS/Programs image, and re-install your backup data. This used to happen a couple time a week, and was a little harder to fix, but the ICH10R driver v. 9.6.0.1014 helped.
The speed advantage between RAID 0, and RAID 10 or 01 is negligible, and the only real penalty is capacity. The difference between RAID 10, and 01 (ICH10R, advertised as 10 but actually 01, I'm fairly certain) is that 10 has more redundancy than 01. Both 10, and 01 can survive the death of one disk. They can each survive the loss of a second disk as well, as long as the second loss is the right disk. With RAID 10, the chance of surviving a second disk failure is 66%, whereas for 01, survival of the array is only a 33% chance.
Raid 5 is a poor choice. RAID 5, like RAID 0, is actually a delayed recycle bin- except that you can recover files from the recycle bin. The advantage of RAID 5 is that you can't fit as much data as with RAID 0, so you won't loose quite as much.