Cliff, if you need it soon, MCDC does have complete 2000 SF3 here:
mcdc.missouri.edu/.../uexplore The MCDC has data down to the tract and block group levels for at least Missouri, Illinois, Kansas, Minnesota, Michigan, and Delaware (state files). We also have the final national file with data for every state, county, ZCTA, place, UA, MSA, etc. in the U.S.