You have a difficult decesion if you are not going to modify your loan and try to stay in the home. Any decision you make if you plan on relocating from your home and the loan balance is greater than your home value will effect your credit. The issue is more about recovery time with existing underwriting guidelines rather than what it is doing to your credit.

Bankruptcy should be a last resort and you should talk to a bankruptcy attorney so you can understand what it will cover and how it will affect you. Bankruptcy will be on your record and effect your credit for 10 years and will affect your ability to purchas a home from 2-5 years after discharge depending on the chapter filed and some of the factors effecting the bankruptcy.

Foreclosure and Deed in Lieu will affect your credit score by 200-300 points and may affect the puchase for 3- 5 years depending on the type of financing you will be going after.

Short sale will effect your credit score 200-300 points and will affect the purchase of a new house from 2-5 years unless the deliquent amount is less than two months and then you can apply for a loan immediately depending on the loan type.

These have been the type of underwriting guidlines used in the past, but with what has been happening things can change.

Good Luck!!
Some good web sites to check out on this subject are:
http://www.homebuying.about.com
http://www.experian.com