New hard drive access speeds

I have replaced the harddrive in my AMD 3500+ computer.
The original drive was a 2-platter 200GB drive. The one I just put in is a 80GB single platter drive. I immediately noticed that my access speeds are significantly slower than with the original drive. Im wondering if this is due to the new drive being single platter . With this AMD system having dual channel RAM, was the old drive accessing both disks at the same time, cutting access times whereas my new one can only access one ? Whats going on here ? Is there anything I can do (new/different driver etc.) to increase my access speeds ?

 

You may have put in a 5400 RPM drive vice a 7200. You may wish to research the model of the drive you put in.

 

Ah. I should have pointed out that the new drive is 7200 rpm just like the original.
sorry