Setting up a RAID array on Linux is fairly easy and is definitely effective. I have even set this up on servers that have hardware RAID equipment because the hardware drivers were either flaky or not available.
Be aware that software RAID will steal some CPU cycles. I feel that most modern hardware has more than enough power to spare but, if you need every ounce of performance then hardware RAID is definitely the way to go. I can say that I haven’t noticed much of a performance hit with RAID running and the benefit has always been worth it but, as they say, your mileage may vary.
This is most easilly accomplished with a recent kernel (at least 2.4 but that covers almost all recent distros). The RAID tools are also usually installed as is mdadm.