Well there are free ones like irfanview but I'd recommend something more along the lines of Roxio's Photosuite or Jasc Paint Shop Pro 9. I use Adobe Photoshop CS myself but thats a rather intense program to learn just to do the basics with an image.
Hey Bolly, good doesn't mean "spend money". I use Google's Picasa software for most every kind of tweaking or effects. Just grab it from www.picasa.com - it's free!
Of course, if you have to have some of that other software, I can probably get it for you. Just ask!