This would be a fast and painless process and it would function exactly as you would expect it to from any other use of WinRAR. You can archive the large file into a small rar file on the first computer, copy that file to your USB stick along with WinRAR Portable and then run WinRAR Portable right off your USB stick on the target computer to extract the much larger file to the new computer. WinRAR Portable is a great solution if you need to transfer a large file to a computer without internet access and all you have is a small USB stick. It archives and extracts files just as well as the larger WinRAR does. WinRAR Portable is simply the portable version of the world famous and much loved WinRAR.
