Don't use DeskTop Manager to transfer files, that is slower than refrigerated syrup.
As others said, don't use Windows Explorer to transfer large files directly to the Pearl; the Pearl's USB port is NOT USB 2.0 so it's about as fast as syrup that has been out of the fridge for about five minutes.
Best bet is to remove the chip and use a USB 2.0 reader like you did.
One of the flaws of the Pearl is not having external chip access. The rumored Pearl 2 is supposed to have an external MicroSD slot.