This post has been deprecated as a better method was discovered. Please see this other post for details.

Full credit for figuring this out for me on IRC goes to Ryan McCue.

I have multiple WordPress alpha installs on my computer. I use them for development and it’s a “pain” having to constantly update them manually. So here’s an awesome solution to keep them up to date automatically.

These instructions are for Vista, but they are likely similar for XP.

1. Using TortoiseSVN or whatever your regular SVN client is, check out a copy of WordPress (or whatever) to a folder. WordPress’ in-development SVN URL is http://svn.automattic.com/wordpress/trunk/.
2. Download and install CollabNet’s command line SVN client (no need for the server). You can use it alongside TortoiseSVN with no problems. If you don’t want to register on their site in order to download, use BugMeNot.
3. Start -> Control Panel -> Administrative Tools -> Task Scheduler
4. On the right, click on “Create Task” (not the basic one)
5. Fill out as follows. Paths will likely be different! Click for bigger versions and hover over the images (even when the lightbox is up) to display the comment text.

Done!

To test it to make sure it’s working properly, delete a few non-custom files from your SVN’ed folder. wp-trackback.php, xmlrpc.php, etc. are good test files. Then click on “Task Scheduler Library” in Task Scheduler (it’s on the left), click once on your new task, and then click “Run” on the right-hand side. If it’s working properly, the files your deleted will be restored.