Well you can look at it two ways, because with 2 36's theres two ways (of raid) to set them up.
You can put them in Raid0 (stripe), which means you'll get the full space of both of them, and access times will be cut in half - Windows will take data needed to be sent to the HD, and send half to each drive, increasing performance.
Or, you can put them in Raid1 (mirror), which means you will only get the space of one drive, and you dont get half access times like in Raid0, but if one fails then your PC will still work fine. Windows just writes the data to both drives, like a mirror, that way when one drive goes, theres the other still.
So saying two 36s is better than one 74 incase of one breaking isnt true, because if you run it in that setup, you only get 36GBs, half the space you bought.
Raid0, you get the full space of both drives, half the access times (which doesnt help anything at all expect video editing, and i mean no performance increase in 99% of applications), and if one drive fails, you lose the data for both of them.
http://forums.2cpu.com/showthread.php?threadid=4584
http://www.realworldtech.com/page.cfm?ArticleID=RWT022201021241
Then again, you can ditch the whole raid and just run 2 drives, but thats the same as raid0 except no half access times, so you might as well :approve:
