As you know, 2.4 came out the other day without *official* support of Windows Vista and Windows Server 2003 (both of which I had 2.3a installed). Well, using Orca and a simple tweak of a setting in the TivoToGo 2.4 .MSI installer, I've got it running on Vista.
Here's how I went about it on Vista
Download and install Orca - http://astebner.sts.winisp.net/Tools/Orca.zip
Download TivoToGo 2.4 - http://www.tivo.com/22.214.171.124-2
Run the TivoToGo installer with administrator privileges
When the installer gets to the point where it says it can't continue due to an invalid operating system, DO NOT click ok.
Point Windows explorer at C:\Users\
\AppData\Local\TempSort the view by date so that the latest files appear at the top
Find the file with a .MSI extension with a random name consisting of alphanumerics with the time and date near when you launched the installer.
Right click on the file, copy.
Paste to your Desktop and rename to TivoToGo24.msi
Click OK on the Tivo installer.
Open TivoToGo24.msi with Orca.
Left click to select the LaunchCondition row in the left window pane.
Remove all entries from the right window pane.
Save the file, exit Orca.
Launch TivoToGo24.msi, install and enjoy.