first thing is to create a swap file on that drive with the minimum and the maximum set to twice the amount of ram you have installed...so if you have 4 GB of ram you want it set to 8GB...it will then be positioned on the outside edge of the drive...that is the fastest part of the drive...
this has to be done first to insure its put on the outside edge...no swap file on the C drive other than the 1 or 2 MBs it says you have to have
then you want to move your my documents folder to the other drive...how to is
here...
after you move it anything you save will automatically go there...
you should also create a new folder on the second drive and name it new downloads then set all your browsers to download to that folder
after all that is done defrag both drives
NOTE...you should never fill a drive more than 80%...if you do your system will no longer be able to defrag and you will bog your system considerably