You wrote to nowhere with the following:

grub-install /dev/sda0

sda0 does not exist. Numbering starts from 1 for Linux device nodes, unlike the bootloader. To not specify a number can mean various things to various programs. For disk utilities, it denotes the entire disk regardless of partitions. For GRUB, it means MBR. Thus:

grub-install /dev/sda

To inject the MBR. Some complex multi-boot setups may need:

grub-install /dev/sdaN

to inject /boot to /dev/sdaN where N is a partition number from 1 onwards, but I personally favour just one unified bootloader on one disk (MBR). Whichever disk has the first boot priority will be hd0 to GRUB. For Windows the standard lines are:

title Windows
rootnoverify (hd0,0)
makeactive
chainloader +1

Which denotes Windows resident on the first boot device, first partition.