http://nayeem.net/novatedlease/
Usually leases are good only if they drop you into a lower tax bracket. Otherwise its better to save as much as you can, then borrow as little as you can.
I have a leas on my 135. Great at the time, tax benefits are good (because of the above)but you are locked in for years. If circumstances change, the cost to pay out the lease will be horrendous.