I'm transferring wirelessly by setting up Calibre as a catalogue in Aldiko and using the Calibre server. Name the catalogue whatever you want (I always use Calibre) and then enter the catalogue url.
Use this format:
http://192.168.1.xxx:80xx
xxx.xxx.x.xxx is your IP address, the last 3 digits can vary depending on your router (do a command prompt "ipconfig", your IP address will be the IPv4 one, google "how to IPconfig" if you are uncertain how to do this, lots of explanations on web)
80xx is for the port Calibre uses (usually 8080), you can check that in the Calibre Preferences menu, in the Sharing over the Net.
PS: using Calibre wirelessly in Aldiko gives you a number of ways to choose which books to transfer including Newest, by Author, by Title, by Publisher, by Rating, series or tags...It also allows you to see the book's metadata before you decide to download with cover art and product description. It also allows you to find and read all your books from any source not just Kobo.
Yes, I could find the book on my SD card once I've copied to it from the computer but the beauty of the Calibre server is that everything is organized and browseable! From anywhere you have wireless! Love it!