Mike, Thank you for including all the information needed to evaluate your home. I suggest removing your last name from your profile.
Unfortunately the short answer may be that while the value of homes in Garden City have decreased due to the market, but you have not capped out on the Taxable Value of your home and they are allowed to increase.
I suggest you look carefully at your assessment notice. I show a 2007 SEV of $61,400 and a Tax Value of $52,349 for your home. In this case values for similar homes in your subdivision would have to decrease below 100,000 for you to attempt getting a reduction in your taxes. The 5 sales in your subdivision in 2007 average sale price was $111,917.
Sorry, I'm in the same boat, however my taxes capped in 2008 and in 2009 if the market continues to decline I will be fighting my taxes.
If you would like more information on the homes that sold in your sub let me know.