To convert pdf to jpg on windows you can use existing open source tools ImageMagic and GhostScript.
Get and Install latest ImageMagic from:
http://www.imagemagick.org/script/binary-releases.php#windows
Ensure that you install with OLE support (for scripting with VBScript)
Get and install latest GPL version of Ghostcript from sourceforge
http://sourceforge.net/projects/ghostscript/files/GPL%20Ghostscript/
Unfortunately there is no GUI for ImageMagic but you can use script below, just save it in pdf2jpg.vbs – to run the script just drag all pdf files that you want to convert on script icon. The resulting images will have the same name but with jpg extension and they will be placed in the same directory as pdf files.
Set imageMagick = CreateObject("ImageMagickObject.MagickImage.1")
For Each name in Wscript.Arguments
pdf = Replace(name, ".pdf", ".jpg")
imageMagick.Convert name, "-resize", 650, "-quality", 80, pdf
next
With ImageMagic you can do lots of cool stuff like create, edit, compose, convert bitmap images, scale, flip, mirror, rotate, distort, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bézier curves.
For more information see command line and COM+ ImageMagickObject documentations.
Instead of VBScript you can use other languages.
Jakub T. Jankiewicz 