I'm assuming by software RAID you are talking about what are commonly referred to as fake RAID controllers - i.e. RAID controllers that offload their work to the CPU as they don't have neccessary intelligence to do so on the card.
I have no trust in software/fake RAID, I've seen a dell precision 390 with raid 1 killed by a power outage. When I got the PC back to base in the end all I actually needed to do was disconnect the primary drive and it booted fine from the 2nd.
I also remember some fun and games with a Poweredge SC1425 (CERC/fake raid) - pair of brand new hitachi enterprise class SATA drives but one had a bad sector, after I had loaded on a certain amount of software the server would continually bluescreen when starting up.
Also remember a Poweredge T105 with a PERC S??? (again fake raid), one drive developed a few bad sectors while in production, the server was taking around 2 hours to boot up and was practically unusable.
Basically with software RAID, in the event of a problem, you should hopefully have a good set of your data on one drive, but don't count on actually being able to do much with it without some kind of intervention.
With a decent hardware RAID controller, rather than continually retrying, if it finds a bad drive it will knock it offline and carry on using the other one.
Myself at home, I'm using a Precision T7400 with a PERC 5/i - the only downside is that it takes a little longer to boot as the RAID BIOS has to do it's thing after the main BIOS, however it's a lot faster than the onboard SAS 6/iR, and also I have the battery backed cache unit, so any data that has been sent to the controller/drives will be battery backed for 72 hours in the case of a power failure before the data gets written, and this then gets written to the drive when the box is next turned on.
The only snag with using a Dell hardware controller is that sometimes they can have moods when using drives not supplied/certified by Dell which happen to be well over the going rate.
I agree with the comments about RAID 1 rather than RAID 5, I'm pretty certain the hardware RAID should support RAID 1 as well, but it may be an idea to check first.