Chris,
I think that unless you have some serious budget then you will be looking at an open source solution - I would expect most budget 'hardware' solutions are embedded/PC + Linux underneath + well known open source packages.
All the real solutions are custom designed hardware and you would have to expect some serious budget.
We've just been demo'ed a great load balancer and accelerator product that is custom hardware, 7 independent CPUs - very clever piece of kit indeed, I'm not expecting it to be very budget.
