Katie1- if its keeping the books on your PC is the problem have you considered using calibre portable? It can be run from a flashdrive or external hard-drive connected to your laptop and the books can be kept with it as one package. It has all the functions of calibre and as Blossom said, will act as a backup of your collections as well. And with davidfor's Kobo Utilities plugin you can also backup other useful info.
It would also be a lot quicker to reconstruct your Kobo collections on a PC monitor than the Kobo?
Good luck whatever you choose
