You can try Drive Image XML: http://www.runtime.org/driveimage-xml.htm

Free and can be used from a boot CD or bootbale USB stick (check out BartPE): http://www.runtime.org/peb.htm

Or just go with the Ultimate Boot CD - it should have cloning software on it but I've never used it: http://www.ubcd4win.com/contents.htm

You'll need to store the image on an external USB hard drive though, or burn the image to DVD's. To be safe, I'd back up all your personal data files separate to the image too just in case something goes wrong writing the image back.

As for the largest hard drive you can use, I'd imagine you'll be fine with the largest laptop IDE drives you can find (320GB?).