I'd rather have one SSD over a RAID 0 configuration. If it's a modest budget then no point going for an i7, they're poor value for money compared to the i5-2500k.
SSD reliability isn't very good at the money. Poor value for money too with sizes being so small. With that in mind I'd rather two fast RAID 0 drives.
Until one of them breaks. 100% of my RAID configs in the past have failed due to one of the drives dying. Use a 60GB SSD now, only cost £60 so I consider it good value for money considering the speed it provides.
It's been a hell of a long time since I've seen HD failire.
Two fast drives in RAID 0 are even better value for money as I can have speed across an entire 2TB, rather than 60gb which is very poor storage these days.
personally I wouldn't store anything important on either; I have my OS / Apps (and selected games) on a SSD and my remaining steam games + other games on a RAID 0, my SSD gets backup up everynight and my photos and music are stored on a RAID 1 array.
At the moment magnetic drives are dirt cheap so RAID 0 and RAID 1 are very accessible options, granted you can get close to SSD transfer speeds for a similar cost, but the random access times is rubbish, this is where you notice the main benefit of the SSD
If you've got the cash get an SSD for windows / applications (you'll need around 60GB for Win7 and apps), if you don't then get a faster drive like the blue of caviar black, the green's are great drives but should only really be used as a storage drive.