E.C.
from googling "Virginia Child safety seat laws" I found the following:
"Rear-facing child restraints must be placed in the back seat. If the vehicle does not have a back seat, the child restraint may be placed in the front seat if the vehicle does not have a front passenger airbag or if the airbag has been turned off." So although it's definitely less than ideal, it's not illegal
Source: http://www.vbgov.com/file_source/dept/fire/Life%20Safety%...
Tips from http://www.car-seat.org/showthread.php?t=19251 -"It's not ideal, but when buying a new/different car isn't an option, you can put a car seat in the front seat of a pick-up. As you said, airbags can be an issue. NEVER place a rear facing seat in front of an active frontal airbag. Push the vehicle seat as far back as it will go to keep the child as far as possible from a frontal colision (the most common type). A certified CPST can assist you with ensuring that the seat is properly installed.".
And I hope that by "booster seat" for your 3YO you mean a forward facing harnessed seat or "combination seat" (Forward facing seat with 5 point harness that can be removed when child reaches the height or weight maximum for the harness, then can be used without harness as a belt-positioning booster seat - yes, the different car seat types can be very confusing :-)). Even though some belt positioning booster seats (seats that have no 5-point harness and merely position the vehicle's lap/shoulder belt on the child) will list a minimum age of 3 years old, the typical 3 year old lacks the size and maturity to sit properly in a booster and be safely restrained by one (smaller booster riders are at greater risk than older/heavier children of "submarining" under the lap belt in an accident). And especially if you have to put a child in the front seat of the vehicle, you'll want the added security of the 5 -point harness. Hope that helps!
Edited to add: even if your child is *within the manufacturer's minimum age/weight/height for a booster seat*, children on the low end of the range are significantly safer in five point harnessed seats - please see http://www.kyledavidmiller.org for more info