Outlook 2007 on Windows 2003 R2 Terminal Services with SBS 2008 exchange server: is instant search available

One of my customers is going to switch to SBS 2008 with exchange 2007. They also have an Open Value Subscription license for Office 2007.
They currently use Windows 2003 R2 as a Terminal Server with Office 2003.

Due to other applications they will need to stay on Windows 2003, but would like to start using Office 2007.

I've read that Outlook 2007 does not support cached exchange mode on Terminal Services.
Is it possible to still have instant search with an Exchange 2007 backend.

I believe there is something called online search which should be enabled on the Exchange 2007 server for this to work, but can't find any definitive answer regarding the topic.