The 1-13 Update is indeed the latest regular database update, and going to "Online" and clicking "Search for Updates is indeed the preferred way of downloading them.
The beta version is available here:
http://studserver.uni-dortmund.de/~su1669/spybotsd/mainappb.zip
This download is
only the SpyBotSD.executable file itself, so what you do, is first rename SpybotSD.exe in your SpyBot folder to SpybotSD.old
Unzip into the Spybot-S&D folder, and rename the unzipped SpybotSD-4-b5.exe to SpybotSD.exe.
Moreover, in order to enable beta
updates, you need to go to Settings > Settings > Web Update and check "Also display available beta versions"
However, these are just that: beta versions, and although problems are exceedingly rare, you try this at your own risk.
I'd advise most everyone to stick to the regular version of SpyBot, and wait until the final version is ready.
In the Languages folder you can delete all other *.sbl files than English, if you don't need them.