A USB memory stick is a solid state drive. Are you happy with the performance you're getting out of your USB sticks? You'll be that satisfied + a bit more, with a solid state drive considering that SATA transfers faster, and has less distance to go to the CPU.
exxe: Considering that the EEEs are powered by a 655MHz, 900MHz and 1.6GHz chip (depending on series number), I'd say it's the processor.