Having just watched engineers try and trouble shoot a RAID 5 set with multiple drive failures, built on Microsoft software RAID, I'd like to chuck my hat in the arena on this subject...
Don't make a software RAID 5 set!
The issue with software RAID 5 sets (especially with Windows OS) is that there is no straight forward way of monitoring the drives within the array, and just as important (as the engineers I was with discovered) no easy way of identifying the drives to establish which are the missing devices!?
Modern hardware RAID controllers are ridiculously cheap and perform a vital role in maintaining the resiliency of your data. These cards also offer a vital source of drive behaviour through active monitoring and at the very least can email you when drives start to misbehave.