Snapraids drive pooling feature sucks but that's not really what the program was made to do. If you want one large drive consider Drivebender or Drivepool. Both have this feature at the expense of disk space due to mirroring of your data.
An i5 would be overkill for a HTPC if you are not gaming. Go with the cheaper option, i3 or Celeron.
To give you an idea, I've got a Celeron G540; it allows me to record 3 shows from a HDHomerun Prime while watching a previously recorded show.