Aneesh, for most practical purposes, one never notices the speed differences between 7200 RPM and 5400 RPM. The only time it will make a difference is while doing a Backup operation. Backups take hours, therefore I do my Backups just before going to bed. So, I don't know whether it takes 4 hours or 6 hours!
Please do Backups regularly. Win 7 "Backup and Restore" in the Control Panel will explain more. Also Disk Image, and Recovery disk. Store the backup on an EXTERNAL disk in a different location.