Either way you'll see an increase in speed full stop.
Buying that you'll get more than speed difference.
if your using 2.2GHz proccessor. Im guessing this next bit btw.
Your not using a Sata drive.
your not using DDR2 Memory.
So you add your sata drive generally gives you slight preformance boost.
DDR2 Memory again given you preformance boost, for multi tasking.
You can have best processor in the world but with out the memory to match your automatically hitting a bottleneck
In my Eyes you'll get nice buy for that. an a noticable preformance boost.