It is hard to find a loan that is really 100% financing, and if it is the rate usually stinks. Most lenders require at least 3% into the transaction (can include closing costs). If you put at least 5% down you'll be looking at the best rate, but you will need to pay PMI.
Remember the 80-20 mortgage payment won't be the same forever. It will drop to the first mortgage payment alone when you've paid off the 20% second mortgage, and you will never have to pay PMI.
There are also some lenders out there that will do 100% financing without PMI, but the rate is higher. I work for Credit Unions here in FL. We don't offer 80-20's but if you can come up with 3%, you can buy a home and won't suffer with a terrible rate. Since you have great credit, maybe you have a credit union you belong to and can check out their programs. If not I'd be glad to see if we could help you out.
