|You didn't say why you switched drives, or where the problem drive came from, so we have incomplete information. If Windows is actually running and just needs drivers, you can download them from Dell support: http://support.euro.dell.com/suppor...|
Link above is for UK. If you need a different country, click "United Kingdom" at top left of page.
If the drive was from a different PC or laptop, you will need to re-install Windows first, then get drivers from Dell via the above link. Windows installed on one computer does not like being swapped to a different computer which has different hardware. You have to install a fresh copy of Windows after swapping the drive.