This is not any type of endorsement for this site, or it's loans. It just has a loan calculator to help you out. Enter the purchase price, how long you want to pay, and what intrest rate you can get;
http://www.bankrate.com/brm/popcalc2.asp
P.S.
IMO leases suck. You pay all that money and in the end nothing to show for it. Buy your car.
Also, if your buying new, secure your financing before going to the dealer. Going through their finance dept. is just another way to get more money out of you.