Many Windows users complain that unlike its Linux and Mac competitors, Vista doesn't have a very good "out of the box" image editor. Paint has been around for many years, with only small improvements. Windows Photo Gallery lets you do some basic image editing (adjusting brightness and color saturation, cropping, etc.) but it's pretty limited. Neither supports layers, lets you sharpen photos or contains much in the way of special effects. Sure, you can get PhotoShop or Paint Shop Pro but that will cost you from one to several hundred dollars. If you need more than you get with the built-in tools but not the complexity and sophistication of the expensive commercial ones, check out getPaint.net, a free image editor that works great on Vista.
You can read about it here: http://www.getpaint.net/index.html