I have 2, 750gb hard drives, that I may put in Raid0 configuration. It will be my first venture into Raid. Later on, if I wanted some sort of data redundancy can I go out a buy a 1.5tb or larger hard drive and set it up as a Raid1 or do I need to go out and buy 2 more 750gb hard drives? It would be more convenient if I can just get 1 larger drive that mirrors the 2 smaller drives in Raid0.
Then again, I could just get another 750gb hard drive and Raid5, but I'm wondering if the scenario above will work.
I highly doubt you would be able to take a RAID 0 array built on two 750s and add in a 1.5 to make a RAID 1. Your best bet if data redundancy is an issue to you is as you suggest making a RAID 5 or having four of those 750s and going for a RAID 0+1 or 1+0.