Yes. In fact, in order to use RAID for data redundancy you must have 3 or more equal drives. Most games are not IO bound, but if your application of choice is say burning CD's or DVD's from HD then IO speed might be important. To use RAID 0 you need only two equal drives.
I think for most gamers their money is better spent on a good quality graphics card, and extra RAM. If HD space becomes a problem, then you might have too much on it and then I would council a CD Burner to archive some of the things you are not using. I archive entire game directories to CD(s) if I set them aside for any length of time. If my HD gets too full (after I have archived anything unused or hardly used) then I consider my HD too small. I would think that 80-120GB of HD should be enough for most home PC's.
I think for most gamers their money is better spent on a good quality graphics card, and extra RAM. If HD space becomes a problem, then you might have too much on it and then I would council a CD Burner to archive some of the things you are not using. I archive entire game directories to CD(s) if I set them aside for any length of time. If my HD gets too full (after I have archived anything unused or hardly used) then I consider my HD too small. I would think that 80-120GB of HD should be enough for most home PC's.