I don't believe there were any graffs in William's Army.

Mentioned in the primary sources are the following nobles:

There was one Duke, William Duke of Normandy.

There were 4 or 5 Counts (a continental title that would not be used in Norman England, the equivalent English title was Earl), Eustace, Count of Boulogne; William, Count of Evreux; Geoffrey, Count of Mortagne, and Robert, Count of Mortain (same place as Mortagne? A son of Geoffrey?).

There were a number of Earls named by the sources with the titles of the English Earldoms they were granted after the conquest, but not always clear what, if any, titles they held previously.

There was one Viscount (another continental title that would not be used in England until much later) Haimo, Viscount of Thouars.

There were various barons (generally referred to as "Lord of someplace" by the sources).

There were knights (knight was not a title of nobility).

When the Normans conquered England they only used two noble titles (for holdings in England) the old English title of Earl (which they kept) and the title of Baron (which they brought with them). Viscount only became an English title of nobility much later (in late Medieval times).

http://en.wikipedia.org/wiki/Companions_of_William_the_Conqueror