
Get with your realtor for some SOLD comps of your neighborhood. If your estimated tax assessments are higher, do make a trip out there to have it lowered. Your dateline is May 30th 2008.
If you had purchased your property in 2007 or 2008, you can furnish the tax appraiser with your HUD settlement statement if the amount you paid if lower than what the County assessed it at. Otherwise, do have comps and photos of the properties you are making the comparison with.
If you have the slightest possibility of selling, leave the values as they are even if your realtor tells you that you are "worth" less. For whatever reason, Buyers who stumble upon the website do feel that this number is "real".
Depending on how far off your comps and your assessment values come in at, do consider having to take time off from work to protest your assessment. If the values are off by a few thousand, then you are only potentially saving very little money. Evaluate if your time is worth your effort.