Your second argument to each VLookup is "DataTable". Change that to Sheet2.Range("PartData").
Btw, after you get that working, you'll have an endless loop. Each vlookup triggers the Worksheet_Change event, so you'll want to add a check for what cell was changed and only do the vlookups if it's the part number cell that was changed.
Thanks Scott. That worked like a champ! I restricted my HotCells variable to be just the named PartNumber cell to avoid the infinite loop.