However the Netbook does have the Canon codec...
Start by removing the Canon codec, then repair/reinstall the FastPictureViewer Codec Pack (which supports the EOS 1D Mk IV just fine) and reboot the computer if asked to do so. There should be only one codec installed for any given file type.
Besides that, all CR2 have an embedded JPEG preview. Older Canon cameras tends to store a smaller image (1/2 resolution) but newer ones, such as the 1D Mk IV, store a full-size preview so our CR2 codec should be left with its default settings (which are to use the embedded preview).
For full-size viewing under Windows XP you can use Windows Live Photo Gallery, which is a codec-enabled application, or our own FastPictureViewer Professional: both with use our CR2 codec to open your files.