Redtop I have a feeling that SLI will be a short life implementation which will never gain full support. But that's just my feeling.
Believe me, even if you have only 2-3 games on your hd when it crashes it's a world of hurt. You'll go through all the driver installations, game installations etc. lose all your saved games and the works.
Raid0 will benefit you only if you do something really intensive such as editing raw video footage. Even for that I'd go for raid 4 or 5 instead.
