Download the avast 5 pro trial (that will give 30 days unrestricted use before having to insert the license file) and save to your existing system and transfer to a USB stick. When you get your new laptop, once you have it running insert the USB copy the installation file to it and run it.
You would then need to purchase your license and I believe there is an offer on at the moment buy one year get the second free or some such. Check out the avast web site.
A direct download link for the full off-line installation file and some info in a pdf file: