Ok, here's the thing.
I can now transfer 3.5 gb worth of data (512mb, 5 times) before the battery goes out on my PicturePad. What I'm wondering is that since you won't be powering the PicturePad on and off with the 4gb card (it's just a straight transfer), will you be able to have enough extra juice to squeeze out the additional 0.5 gb needed to transfer the full card.
If there isn't enough juice, I'm willing to stop shooting when the card is about 3/4 full, and then transfer between 3 and 3.5gb, but if I forget and fill the card....
I'll give Delkin a call and ask them about the situation.