Experts agree: there is no type of infant walker with wheels that is safe, and parents should avoid them altogether.
A walker is a seat suspended on a circular frame with wheels. Ideally, your child would sit with her feet just touching the floor and be able to get around with little effort. It was once thought that a walker would encourage your child to walk (hence the name) and be a safe place for your child to stay. Unfortunately, neither is true.
Thousands of children per year are injured when their walkers turn over an object or small toy and they spill out onto the floor, down the stairs, or into a pool. The walker also allows the child to travel to places where you might not expect your child to be, such as near a hot stove. Fractures of the skull, arms, and legs as well as burns and cuts have been associated with the use of infant walkers.
The muscles used by a baby to move in an infant walker are different than those used to walk. The movement skills acquired in the walker are not very useful in learning to walk out of the walker. Also, in a walker a baby cannot learn the balance skills needed to walk without assistance and he may not have the motivation to learn mobility when he's received it from a walker.
Exersaucers are a good alternative to walkers; they do not have wheels and are designed to prevent children from tipping over. Your child will be very happy in the short run and you'll know your doing the best for your baby in the long run.