Decreasing touchpad sensitivity

I have found increasingly that after supposedly single-clicking on a file, often it will open up (without my wanting it to). I thought it was b/c I had Windows set to open up on a single click, but in XP's file settings, sure enough, Tools>Folder Options>General tab, I already had the setting double-click to open, single-click to select checked.

So what can I do? Is there a mouse/touchpad sensitivity setting I can change? What setting/number would be good for this? This is the only thing that I can think of that would be causing this, with the above folder option already checked.

 

OK I found Mouse in the Control Panel, and selected the Touch Pad tab.

Not too sure I understand the options. One of them said Touch Sensitivity, and so I moved the "marker" one notch over towards the "heavy touch" side, and away from teh "light touch" side, which I assume means that it will be a bit less sensitive towards my own clicking.

There are three options at the top. The first two are selected, but not the third.

Tap to click
Tap and Drag
Locking Drags

????