Don't forget to check the laws regarding car seats. They have all been changed in November for Victoria and NSW. I 'think' you must leave them rear facing until a minimum of 12 months of age. Just something else to consider.
aooarently its only minimum of 6 months..
Summary of changes
The new national child restraint laws state:

Children younger than six months must be secured in a rearward facing restraint.
Children aged six months to under four years must be secured in either a rear or forward facing restraint.
Children aged four years to under seven years must be secured in forward facing child restraint or booster seat.
Children younger than four years cannot travel in the front seat of a vehicle with two or more rows.
Children aged four years to under seven years cannot travel in the front seat of a vehicle with two or more rows, unless all other back seats are occupied by children younger than seven years in a child restraint or booster seat.
from the NSW rta website this morning..