as jim said, just copy your show directory.
example: my show directory is C:\Users\sean\Documents\xmas2014
if i go into there and copy everything to a usb flash drive, I then go to a new computer and copy the contents of the flash drive to
c:\newshow_xmas2014
i then launch xlights on the new computer and the first thing i do is set the directory with a "File,Set Show Folder" command to c:\newshow_xmas2014
it should come up and be an exact copy of what you had before.
everything that is a model is stored in your xlights_rgbeffects.xml files.
all the data in a grid is stored in the sequence xml files.
xseq files are the least important files you have as they can be recreated with the sequence xml and the sound file. If you lose the sequence xml then you have lost all the work you did setiing timing, putting in effects. None of that info is stored in an xseq file. xseq is a fully rendered, binary file that is used for playing the show.
follow the copy procedure above and you get all your pictures, sound files, movie files, xseq files and all xml files. In other words, eveything.