I agree that hardware RAID is expensive (and somewhat inflexible). Those are some reasons why I use software RAID. I have used Linux software RAID with RHEL a few years ago on a number of SunFire servers (Opteron version). Currently I use Debian 5 ("lenny") software RAID on a server (VMWare Server 2 virtual machine host and guests) Intel Xeon, and a companion workstation AMD Athlon. Both of those are 64-bit and use SATA disks, both have fake RAID, and in the Intel I turned the fake RAID off in the BIOS settings (I haven't needed additional SATA disks for the workstation yet, so I'm using the standard controllers). I have also used software RAID on 2 SCSI disks in an older IBM NetVista with SuSE 9. (As an experiment, I recently used Debian to build a number of RAID configurations, culminating in a a very interesting RAID10 array with 4 SCSI disks on an AMD dual-CPU Athlon -- http://en.wikipedia.org/wiki/Non-sta...nux_MD_RAID_10
The software is already available on the install CD / DVD media. The install took me a few attempts before I got what I wanted (I always allocate time for a number of installs, so that I get used to the choices and steps).
With Debian (either 32-bit or 64-bit), you use manual partitioning. Assuming you have deactivated the fake RAID, the install can proceed more or less normally. You partition each physical device first, then you assemble the array(s) from those partitions. It's slightly more complicated if you want to involve LVM. I have done that only with RHEL, and not Debian. There is a HOWTO at http://www.howtoforge.com/set-up-a-f...id1-lvm-system
that includes encryption. There are other topics at howtoforge that might be useful.
I'm assuming that you know that if you lose any disk in a RAID0 set, you will lose everything. I used RAID0 for speed once for a very short project, but I did, in fact, lose some work because of a bad disk. I might be tempted to use RAID0 again, but never for the OS itself or home directories.
On the other hand, the flexibility of software RAID allowed me to use 2 SATA and an IDE in an array.
Best wishes ... cheers, makyo
( Edit 1: typo )