Is it showing up in BIOS? One thing you can do is get (download it for free - burn to a CD) a Linux LiveCD like Ubuntu 9.04 and run that (it boots off the CD - don't install it, just "use without making changes"). Then check the Partition Editor in the Menu 'System>administrator>partition editor'. It should detect your hard drive and you can even format it in NTFS right there. If the hard drive doesn't show, it may be faulty. Reboot the system after formatting to NTFS (remove any USB drives, external drives, etc. before rebooting) and go back to installing Vista. If it still isn't detecting your drive, press Shift+F10 at the part you should be selecting the drive, it will open a command prompt. Type the following text in quotes:
'diskpart'
'list disk' - you should see a list of drives. If only 1 hard drive it should be disk 0
type 'Select disk 0'
type 'list partitions' - you should have at least one partition if you formatted using the Linux Partition Editor.
type 'select part 1' (or whatever partition is listed).
type 'active' or 'activate' (I forget the exact command, if you type it wrong a help menu will come up) - that should activate the partition for Vista to use.
Type 'exit' twice- you should return to Vista and the list of hard drive(s) to install Vista on. Choose the 'Refresh' option. Then you should be able to select your hard drive for Vista to install to and proceed.
Good Luck!