Whatever you do don’t offer an ultimatum UNLESS you are prepared to act on it.
Professionally it is best to use your seichel, if you know the company is struggling don’t ask for that raise. Often bosses of struggling companies offer liberal praise for a job done (well or poorly) to keep their employees. When you confront them with a demand (no matter how you phrase it, the boss understands your demand) they might tell you to be thankful you have a job in this economy.
Eitzah Tovah, know your boss well, know the finances of the company well, and know if you can truly afford to find a job in September 2009 with the health of the economy.
EDITED