|You need more details....|
Is this a new drive?
Is this a working computer with an OS on another drive?
Is this a new build?
Are you replacing a bad drive?
Does the BIOS recognize the drive?
Do you have a new Windows 7 install disk? Recovery disk?
Does the install ask you to partition/format the drive?
Have you selected Custom and Format/Partition when you try to install?
THEN: List all hardware or system specs.
THEN: Describe the problem in more details.
THEN: We can help.
You have to be a little bit crazy to keep you from going insane.