Yea, raid is great, I bought that extra 750 caviar black just to do it with, and it really did help. And for me, data loss isn't a big issue, I build and repair pc's for a living and I'm always adding, modding, reformatting, all that. (which I am trying to do less of) but for someone who needs it running 24/7 with no hassles or issues, I would at least keep stability and reliability in mind. Theres nothing worse than working an entire week on a paper, and having a hdd crash the night before its due.
The only reason I even stated it is just because when using raid 0, if one drive goes, both go. So if this is a route you decide to go, make sure you get a good drive, like a WD Cavier Black, or a Spinpoint F3 (although I think the Black has a better track rec, and a longer warranty), and on top of that, an external for backup isn't such a bad idea either.
After thinking about all this, my biggest question is.. why not get a laptop now?
If your desktop is still keeping up... why not just put a little bit more ram in it, a better cooler, over clock it and call it a day. Then go out and spend the rest on a laptop now.
A laptop is very handy when having to go from class to class across campus. And even if you don't use it as much the first semester, it'll give you time to set it up, get the software you need, and become used to it.
One big thing a lot of people don't know (users who are mainly desktopers) is that scrolling and moving around on a laptop (without a mouse) can become difficult and annoying to get around. So I highly, highly recommend getting a laptop with an oversized multi-gesture pad.
That way you can use the 2-finger scrolling, so u don't have to move it over to the side everytime you need to scroll. Also, zooming, rotating, and gestures come in handy, especially when launching new things (talking about gestures)
I just bought my mom an Acer Aspire 5750-6421. Paid $399 for it new.
It has an i3-2310 (2.1ghz) Intel HD 3000 gfx, 15.6 HD LED backlit lcd, 4 gb ddr3, 500gb hddd, dvd burner, and b/g/n wifi. It also has hdmi, a card reader and hd audio. And of course the webcam.
Oh and it has the multitouch pad, which is nice.
You really can't beat that for $399.
Just thought I'd share my experience, it's good computer.
(I didn't like Acer much b4 just bcuz they mostly target the low budget crowd which usually comes with lesser quality, but I am happy to say their quality has increased a lot and it feels like I'm using a $700 laptop)
If you're going the netbook route, spend that bit extra and grab one with a ssd, use an external for your vids and all, for easy transfer between.