Everyone in here said the right thing.

Be honest
Don't burn your bridges(as best as you can) - Keep with the job you'll be happier at. If more money makes you happier, obviously stay with the server position. But at least if you tell the previous boss your situation, at least even if you do break the 2 week resg. letter, you'll know that at least you tried to explain it to him.

Later, QD.