I agree with this advice, and it is entirely doable on an HTPC:
I have been taught that its best to have a small, fast primary drive for the OS and then a larger secondary drive for data.
The reason for this is that if the OS becomes corrupted and you need to reinstall, this setup allows reformatting/reinstalling the system drive with no need to touch the data partitions.
But I can't recommend RAID solutions.
If you absolutely need the performance, go with hardware RAID-0, keep good backups, and be prepared to restore from backup at the first hardware failure.
If you absolutely need the redundancy, a RAID-1 mirroring solution -- preferably software RAID -- is best.
Why? Two words: hardware failure. Hardware RAID is chipset dependent. You cannot take a RAID set from one chipset and plug it into another and access your data. Software RAID is slower, but doesn't depend on a RAID chipset. In the event of a controller failure, you won't have to locate an identical controller chip to get a software RAID set up and running again.
Personally, I use standard partitions on bare drives -- no RAID, no LVM, no Dynamic Disk. I have a spare drive in the server to backup the important stuff, and another offline that gets plugged in and updated once in a while. That protects me from a drive failure. If the motherboard or drive controller fails, these drives will work immediately on any other hardware. I don't need to find matching chipsets, I don't need to configure a new system to use another system's software RAID set or LVM, and a single drive failure has no effect on my ability to access other drives.
Remember, RAID is not a backup. RAID is not a substitute for a backup. RAID-0 is for performance, RAID-1 is for redundancy, RAID-5 is for a little of both. There's another piece of advice that's worth keeping in mind:
There are only 2 kinds of people in the world: those who have experienced catastrophic data loss, and those who will experience catastrophic data loss.