Reving up the spindle doesn't work because the read/write head circuit will only read/write so fast. It's tied to platter rpms.
As for stepping up the voltage all you do is blow out the driver chips.
Now for some real and serious tweaks.
In the device manager you find the IDE ATA/ATAPI controllers.
Click the plus sign next to it. On each of the channels click> scan for hardware changes. This updates the channel to any changes you or the system has made to a device on this line. Next on the same menu you found scan for hardware changes click on properties. Select the advanced settings tab. Under both devices pull down the menu and select> use dma if available. Clicking apply and ok go all the way back to the desktop and reboot. AAAAAAAAHHHHHHHHHHHHH nothing like a freshly booted system. Now if you keep the little darlin cleaned up you have nothing else to do. But if you don't let me point out a handy little program that's like nothing else you've seen and that's crap cleaner.
(edited again because I forgot to put the link in)
It does just as its name implies. Cleans out the crap you didn't know you had. First time I ran it it found 98megs of pure crap.
Drive performance can be inhanced just in keeping the system cleaned up. Run your ad/spy ware and anti virus programs often. Defrag often. It doesn't hurt the drive and any one that says different is not being honest.
Set aside a time to run your maintaince program and stick to it. OH and do those back ups. It's getting to be the change of season and that means thunder storms. Lightning can be a system killer. So when a storm comes barreling through shut down, unplug, and go watch the storm. Any more tips I can give I'll be happy to pass on. Just ask.
Edited because of derailed train of thought errors...