If your hard drives are set as standard IDE or SATA then they should be seen in the BIOS. However, if you have set the controller to make the disks perform in ACHI mode, then (depending on the BIOS) you might not be able to see them - but you should see them listed during the boot sequence.
Depending on the chipset which is controlling them, you might need to install the corresponding chipset driver once you are in Windows 7. This used to happen to me using Vista x64, but once I had installed the correct driver, it gave me the message that new hardware had been found and then went on to (slowly) list all the missing drives.