Moved to Hardware Support
There are a few posts in these forums about the 750. Try the "Search" link on the upper left-hand corner of this page - you might find clues in some of those other threads.
Sierra Wireless did actually have an H/PC 2000 driver for the 750, but we've never gotten hold of it to put in the Hardware Compatibility List. If any other users here still have the driver, we'd appreciate it if you'd share it with us.
(The links from Sierra's Web site mentioned in the threads are all dead since the 750 went end-of-life a long time ago.
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Both Pocket PC 2000 and Pocket PC 2002 are based on CE 3.0. It might be possible to get one of those drivers to work, but as C:Amie said, the API sets are not identical between the Pocket PC platforms and H/PC 2000, so it's basically hit-and-miss trying to add Pocket PC DLLs. It could take a while finding the right combination - if there is one at all.