Faster CPU won't do any good here. More RAM and make sure your swap file is setup large enough (I'd set it for at least 2 gig in your case), and ensure you have several free gig of hard drive space. A faster video card may help with the rendering, CS5 should be able to use the GPU on the video card. If you have the money, get a pro level card like a Quadro or a FireGL. The dedicated drivers are good for Adobe.
You won't see much speed increase if you just lower the timings, you will see a benefit if you can overclock the CPU and RAM speeds first. Careful with that though if you have not done it before. Something you may want to look at, is a SSD, rendering programs use the drive a lot, and a faster drive will make is run faster.
Your WD Black is a good drive though, so the SSD really depends on your budget. If you can spare the couple of hundred for a drive, you'll be happy with the upgrade.