After not being able to look at any images of the 1940 census yesterday, I made a lot of progress today, finding all 4 of my grandparents! The fastest way I found to search the images was to download the entire enumeration district and then flip through it in Windows Live Photo Gallery.
Grandparent number 1 (according to my pedigree chart), and the second found today, is my paternal grandfather, Theodore Acquard. In 1940 he was 6 and living on a farm on Alleghany Rd. Bennington, Wyoming Co., NY. He is listed with his parents, Florian and Stella (Karpinski), younger brothers Daniel and Ronald, grandfather Joseph Acquard and uncle Walter Acquard. His name is misspelled as “Theadore”.
Source: 1940 U.S. census, Wyoming County, New York, population schedule, Bennington, enumeration district (ED) 61-8, sheet 7B, dwelling (blank), family 150, Florian Acquard household; digital images, National Archives and Records Administration, 1940 Census (http://1940census.archives.gov/ : accessed 3 Apr 2012); citing National Archives and Records Administration microfilm T627, roll 02816.