> Is SSE(2) inherently faster then (at least in real-world implementations) than x87, even when you don't vectorize?  Would I be able to expect any speedup from going from x87 to SSE(2) for code that has a decent amount of implicit instruction level parallelism but wasn't explicitly vectorized either by me or the compiler?

There is a couple of interesting scalar instructions in SSE

- cvttss2si : floorf without modifying the rounding mode (SSE2)
- 32-bit float square root and inverse square root
- min, max

SSE doesn't suffer from denormalization which can be very useful.
I personnally don't mind if the compiler use them or not, provided one can use inline assembly :)