I usually blog from my laptop and when I type, the cursor points from one place to another. This slows down my typing speed and also wastes time as I again have to place the cursor at the appropriate position. I use an optical USB mouse, so actually speaking, the touchpad is of no use and rather, only creates problems.
Should you wish to disable it, you can dos so easily in Windows 7! However I would rather suggest you to only disable your touchpad while typing.
How to disable your touchpad completely:
Windows 7 by default, automatically detects your touchpad and for disabling your touchpad completely, you will need a 3rd party software.
Most major and renowned laptop manufacturers like Lenovo, Asus, Dell, Acer, HP, etc get the touchpads for laptops from a 3rd-party OEM provider. These providers have some official drivers on their website that you can use for disabling your touchpad in Windows 7. These drivers are available here at Touchpad drivers for Windows.
There is also a list of Supported Operating Systems at the above mentioned link. You make your selection and then download.
How to disable your touchpad only while typing.
This is actually a better and simpler method as it solves the problem more quickly.
TouchFreeze is simple utility for Windows NT/2000/XP that solves the problem users may face when they are typing a document and the palm of their hand accidentally brushes the touchpad, changing the position of the cursor in the document or accidentally clicking on an option. It automatically disables touchpad while you are typing text; like Syndaemon on x-windows.