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There is nothing really wrong with your version. However, it is a bit wordy -- by American English standards -- and slightly too formal -- again by American standards. Also, one sentence does not quite have the right "spin." Here is a different version:

<I am pleased to inform you that> My birthday party  is taking place on  October 11, 2009 at my residence at 7pm.  It would be my great pleasure to have you and your family among my guests.  My whole family is eagerly awaiting your arrival.

The phrase, "I am pleased to inform you" is a bit formal. I debate with myself whether to drop it or keep it. It is not necessary, but it is not wrong either.

"I am sure you will not disappoint us" puts an obligation on your guest that is not appropriate in American circles. Your guests only obligation is to tell you whether they are coming. To ask for more is considered rude. Now, I know that is not what you are trying to say here -- but it is what the words convey. The words make it the guest's fault for creating disappointment. With a slight change, you can place the onus back on yourself. "I would be quite disappointed if you cannot attend." Now you create the disappointment yourself. I do not think either sentence is needed, but if you do keep one -- don't blame the guest.

I hope this helps.