Arduino uno bootloader issue and flashing of sketches

The fuses look valid for a 512 byte bootloader. The bootloader is loaded into high memory - 512 in this case. The compiled sketch starts at 0.

If you have another board you could use it to work out which bootloader (if any) is actually there:

Try selecting Duemilanove from the Board menu. It is quite possible to have that bootloader on a Uno board.