I've been looking into RAIDs for awhile. I've used an Adaptec and a 3Ware raid controller for awhile and found them very useful and high quality with great support in linux.
Since then, I've found that there are a few other options:
- Full software RAID in linux using the md tool
- Pseudo fakeraid using a bios-powered raid using a tool called dm
The choice here is clear: if you are using a dual-boot setup with Windows, you cannot go with a full software RAID solution, you have to use dm or a hardware controller. If you don't have to dual boot with Windows, definitely use the software raid. I also use a software raid on my mac. See Disk Drive Notes? for more information.
External RAID Links:
Mailing list with some good info about page, block and stripe size. http://www.tldp.org/HOWTO/Software-RAID-0.4x-HOWTO-8.html - TLDP is really great, if a bit dated at times.