Assuming the Vodafone VPx is definately an HTC Blue Angel then yes you should be able to install the T-Mobile rom. But if there's nothing wrong with the rom you're using then I wouldn't recommend it.
As far as the T-Mobile upgrade file, as long as your device has been unlocked for any rom then it'll run fine. If not then things are more complicated...
...in order for your device to be unlocked for any rom it must have been unlocked by www.imei-check.com or by a tool (such as those found at XDA-Developers.com) which resets the CID to factory default. By doing so the device is unlocked to any providers rom.