It's not ready to divide calculations between 8 threads running in real concurrency.
Just to clarify your statement, you mean that the software
is not ready, right? Because the hardware certainly is (assuming you're not too memory bandwidth limited, at least).
And sure thing, normal people won't be able to even nearly
utilize a octa-core system, not even a quadcore. But for 3D rendering, servers (especially those running multiple VMs) et cetera, those CPUs can be utilized, and are welcome.
I'm interested in a 4-500 budget dual core-intel.
I assume you're talking US$? And would that be for just the CPU, or total system?
$450 can get you a core2quad Q9450, which is a damn fine CPU, and the one I wanted - but not on stock yet, so went for the ~$345 Q6600, which is also OK. The best bang for the buck is probably the dualcore E8400 at $250. Not much point in going lower than that, since the price differences in that segment are so small.