You can save images inside a PDF file as a clipboard item and then paste them into any picture viewer (Photoshop, Paintshop Pro, GIMP, MS Paint etc.) and save from there in any format you like. No further/additional software is needed.
I am using the latest free Acrobat Reader X but it should be very similar in all the earlier reader versions.
1. In the top menu bar go to 'Edit\Take a snapshot'.
2. Drag a box around the image you would like. The image is then copied to the clipboard.
3. Open your picture manipulation software of choice and select a new file.
4. Paste the contents of the clipboard into this new file, crop off any excess pixels and save in whatever format you like/need.
Job done!