Move your cursor up to the top right of the Google Earth window and you'll see an outline of a small man. Drag this to the street you want to look at. If there is a Streetview for the area then the roads will highlight in blue. It won't work/appear until you zoom in close enough for roads to appear.
You can also use Google Maps. On Google home page there is an option at top left of page to search maps. Put in postcode or place name and then drag the little yellow man onto the road you want to view. Depends on where in the world you are viewing as to whether or not you can actually 'drive' along the street.
Street view in the latest version of Google Earth isn't quite the same. Don't look bottom left or any of the layers. Zoom down until until you are about 500 km above the surface move your cursor right over the zoom and direction controls and the pegman (pegperson?) should appear then drag it to where you want.