DownloadPsychtoolbox fails (Windows 7)

I am trying to install PTB on a Windows 7 machine (AMD E-350, 2GB ram).

I am running Matlab 2012b.
I installed "Slik SVN 1.7.8" with a "typical" install.

How can I make "svn" be a recognized command??

Any tips appreciated,
David


Here is the error message:

>> DownloadPsychtoolbox('C:\PTB\')
DownloadPsychtoolbox('C:\PTB','beta','')
Requested flavor is: beta
Requested location for the Psychtoolbox folder is inside: C:\PTB

Good. Your privileges suffice for the requested installation into folder C:\PTB.

I will now download the latest Psychtoolbox for Windows.
Requested flavor is: beta
Target folder for installation: C:\PTB
The following CHECKOUT command asks the Subversion client to
download the Psychtoolbox:
svn checkout https://github.com/Psychtoolbox-3/Psychtoolbox-3/branches/beta/Psychtoolbox/ "C:\PTB\Psychtoolbox"
Downloading. It's nearly 100 MB, which can take many minutes.
Alas there may be no output to this window to indicate progress until the download is complete.
Please be patient ...
If you see some message asking something like "accept certificate (p)ermanently, (t)emporarily? etc."
then please press the p key on your keyboard, possibly followed by pressing the ENTER key.

'svn' is not recognized as an internal or external command,
operable program or batch file.
Sorry, the download command "CHECKOUT" failed with error code 1:
'svn' is not recognized as an internal or external command,
operable program or batch file.

The download failure might be due to temporary network or server problems. You may want to try again in a
few minutes. It could also be that the subversion client was not (properly) installed. On Microsoft
Windows you will need to exit and restart Matlab or Octave after installation of the Subversion client. If that
does not help, you will need to reboot your machine before proceeding.
Another reason for download failure could be if an old working copy - a Psychtoolbox folder - still exists.
In that case, it may help to manually delete that folder. Or maybe you do not have write permissions for the target folder?

Error using DownloadPsychtoolbox (line 765)
Download failed.