[EricH]

No. You do not have to attach a Jaguar. You can also attach a Victor or a Spike, or in the case of a VEX motor, there is a VEX speed control.

I would suggest reading Section 4.1.8 of the Manual very carefully, particularly [R48], [R50], and [R51]. That is the allowed motors list (and I would note, no motors in that list are 5V or 10V that I know about), the rule governing exactly what controls the motors, and the rule governing what speed control devices are legal to be used to control motors.