The set usually comes with a car seat base, which easily installs in the backseat of your car. When you go out, you place your baby in the infant seat and snap the seat right into the base. Its simple. A perk of this is that when the baby is sleeping, as most do in the car, you can just leave them in the seat and not have to worry about disturbing them. This also works going in and out of the stroller.
These days, since the American Academy of Pediatrics changed their recommendations stating that children should face rear until they are 2 years of age, more and more infant seats are being made to suit babies up to 30 pounds. Most baby companies make Travel Systems. Some of the more popular ones are Eddie Bauer, Graco and Evenflo. You can buy them at any store that offers baby products, such as Babies-r-Us, Target, Wal-Mart and Sears. However, please note that the parents-to-be will most likely have which Travel System they want on their baby registry, so be sure to check that before you make any purchases. Trust me, Travel Systems are not cheap, so you do not want to buy the wrong one.
If you want to spoil the new parents-to-be and buy them a gift they will never forget, then by all means, treat them to the Travel System of their choice. Happy Shopping!