Been diddling with this for over two years. Never found a solution by either experiment or posting here nor Google. The basic problem is that VAIOs ship with a funky proprietary UI for managing the Toschiba BT stack, thus no BT dialog box in Control Panel. Sony techs say it's a Treo problem, and around with with them and uSoft. The non-Sony folks can't figure it out because no Control Panel entry. Gave up and bought an HTC FUZE; same problem! So searched again and found a procedure on a uSoft-related site that spoke directly to this problem. When I was successful with the FUZE, I powered up the Treo and doggone if it didn't now work too.

So here's the steps; take them exactly in order and you should be able to sync your Treo 750 to your Sony VAIO via Active Sync.

1. On Control Panel/Device Manager: right click and uninstall *every* BT-related entry. When asked if you want to delete the driver too, click "yes." This goes for the whole BT section, and also look for the Toshiba stack in the "Other" section, perhap with an "!".

2. Go to "Programs" and uninstall the Toshiba BT stack application.

3. Turn off everything in site that is BT.

3A. (forgot this, don't want to renumber). Delete all pairings.

3B. (forgot this too), delete any association on WMDC between your TREO and AS, including USB.

4. Restart your PC.

5. Download the Intellipoint 6.2(32bit) for Windows Vista driver; sorry I lost the link.

6. Install the driver. Makes no difference if you have an Intellipoint mouse or not; just pick one and install the driver. What it is doing is installing the uSoft BT stack. Do not configure a mouse, just pick one or it won't install.

7. If VAIO, Vista, etc, asks if you want them to find and install a BT driver for any reason, say "no." If asked for a driver, select "manual" and pick "Microsoft Driver" of "Generic Driver". This is from the directions I found. When I did this the system seemed to just automatically find the driver, so I never had to respond to this.

8. Open Control Panel. Aha! You have the uSoft/Vista BT dialog box now. Check that all of the BT hardware on the Device Manager has the uSoft BT driver selected. The dreaded Toshiba stack is now just a bad memory.

9. Open up BT Devices (still in Control Panel), and add your Treo as a new device.

10. Pair the Treo to the VAIO. When paired, it will now finally, thankfully, show ActiveSync as a service. Interestingly, no COMM port is needed, and "Add port" selection window doesn't show any.

Now just launch WMDC first, then "connect, and you're on the road.

The uSoft poster had a few dozen follow on postings that everyone that tried it was successful. Hope it works for you as well.