Well RAID 0 is unreliable, in that if one drive fails then you're stuffed.
I've owned a SSD in the past. The 2nd gen Intel 160GB SSD. I didn't see as much benefit as I was expecting for the £300 odd I'd spent. Yes it was fast but it didn't make everything magically instant like I was expecting.
Reliability of SSDs is a bit of an unknown at the moment. They have a finite life span when it comes to writing data. How long it lasts depends on how much you hammer the thing. In theory you should know well in advance before the thing fails as it can keep track of how many writes its done.
Some good choices of components there though. Make sure you get a quiet CPU cooler. Long list of recommended ones here Recommended Heatsinks | silentpcreview.com