I just bought windows vista Home Premium but
when I try t install it, i get to the point where it
asks me on which hard drive i want to install it.
i tell it to install it on my new 500GB hard disk
and it says that windows does not find a size suitable
for vista to install
With multiple HDDs in a machine you may be better off disconnecting the drives besides the installation designated HDD and using the bios to select the boot drive after the installation is completed and all the HDDs are hooked back up.
Partitioning and formatting the new HDD are definitely going to have to be done to be able to install any OP/SYS.