[GregT]

If you have a mouse with a wheel...

Hold down the middle mouse button (wheel) - this will pan the view
Move the scroll wheel in and out - this will zoom

To zoom to a specific part (or parts):

Select the part you wish to zoom to (for multiple parts hold down ctrl while you select them).

Hit the "zoom to enities" button on the view toolbar (I attatched a image, the button you want has a red box around it in my image).

Greg