Set up your report with the base fields you're looking for. Add tblFloppy. Add tblFloppy.Size to the report for the drive capacity in bytes.
If you're not interested in USB drives (including some printers), you'll want to filter for tblFloppy.InterfaceType <> 'USB'.
If you're wanting the capacity in megabytes or gigabytes (the advertised capacity), use tblFloppy.Size/Power(10,6) or tblFloppy.Size/Power(10,9), respectively. If you want mebibytes/gibibytes, use Power(2,20) or Power(2,30) instead.
If you want to more closely reflect the advertised capacity, convert the megabytes/gigabytes to integer, truncating the decimals, i.e. Convert(Int, Size/Power(10,6)) or Convert(Int, Size/Power(10,9)).