After losing a ton of stuff on one those infamous IBM Deathstar drives, I backup habitually to multiple drives.
I can't recommend SSDs as a boot drive enough and I've got no idea where that slowdown after 128Gb BS is based on.
They boot quickly, they have ultra fast access time, don't need defragmenting EVER and in the case of Sandforce based drives, don't even need TRIM because they handle it internally.
I can't think of a better setup than an SSD as the boot drive and the original drive as extra storage for iTunes etc... apart from maybe using a 7200rpm HDD alongside the SSD for the best of both worlds. I use multi-track audio so as a tie over, I'm currently still booting from the internal 5400rpm drive till I can get a firewire case for my 7200rpm drive. They're cheap now so if I was starting from scratch, didn't already have one and was using a laptop, not a Mac Mini, I'd just buy a fast SSD like a Vertex 3 to boot from, a fast 2.5" 7200rpm drive like the Western Digital Scorpio Black and an optibay or equivalent to mount the SSD in.
I use the optical drive from my Mac Mini externally with a £6 USB to optical cable and it's fine like that.