HUBZone Improvement Act of 2007 - Amends the Small Business Act redefine a Hubzone Qualified Area to count as a qualified nonmetropolitan county any county located within a metropolitan statistical area if: (1) its total population is 80,000 or less; (2) the population residing within the county's urbanized areas is 10% or less of the county's total population; and (3) the county meets either a specified median household income or a specified unemployment rate requirement.