ok! i checked the settings in BIOS... It turns out that the setting for both my disks says:
PIO Mode: 4
Ultra DMA Mode: 4
And windows indicates that those disks are using Ultra DMA Mode.
But when i come to the DVD writer, it says:
PIO Mode: 4
Ultra DMA Mode: 2
And beside this info there is a text:
WARNING: Ultra DMA mode 3/4 can be enabled only when BIOS detects shielded 80-pin cable.
I thought i had one of thouse, but i'll guess i have to go down to the store later an get one? So can I convert the disk to NTFS in the meantime