When I'm working at Home I use FireWorks to scale images.
At work, where I'm limited to free programs, I use
GIMP.
Also on the topic of free programs, the following are also
really helpful:
Textpad -- Great Text Editor, way
better than Notepad or Wordpad
ColorPic -- Great for
finding out what color a particular logo is so you can duplicate
the color code in your HTML or CSS
FireFox -- Even though I
develop for IE, I use FireFox when programming JavaScript for the
HTML validation and JavaScript console.