How bad is your leak? if the system will hold pressure for any appreciable length of time you might consider a sealant. i have had excellent results with this product
Cliplight Manufacturing - Automotive - Super Seal Premium. It has been over a year since I originally put it in and I have not had to add any refrigerant since.
The cooling ability of the system doesn't seem to be affected either. You have to make sure that the system is bone dry prior to installation.