> > I dunno about this specifically, but one other "perfect
> > interpolation" would be to compute the DFT/FFT of the
> 
> NO.  You'll get a perfect interpolation of a hypothetical 
> periodic signal of which the FFT is the transform.  That

argh. i edited this sentence so often that it ended up being 
wrong...  Right is that an n-point IDFT will give you an n-point 
signal, just as an DFT of an n-point signal will give you--you 
guessed it--an n-point DFT.  Hence, you will still need to interpolate.