Getting a car and driving in Dubai

What is the deal with driving in Dubai?  Assuming I will be working somewhere downtown will I need to buy/lease a car?  What happens to my American liscense?  Do I need a UAE one instead?  How expensive are cars to lease?

We don't have a viable public transport system, so private cars are how we get around. The traffic is horrendous and finding a parking space is all but impossible.
Or you can use taxis.
When you have your residence visa you must get a Dubai driving licence. You can't buy a car until you have the res visa.
Prices are cheap. For example a new Toyota Camry is AED55,000 (US$14,950) a Dodge Charger is AED84,500 (US$23,000)