You should be very concerned! The click is the sound of the beginning of the end for your hard drive. Replace it immediately with an SSD (sold state drive). It will make the computer faster than it ever has been.
Simple to replace on this model:
Dell Inspiron 1545 Hard Drive Replacement
You will need to either back up or copy the old drive. Some SSD brands come with cloning software . For example, Samsung has “Data Migration” which is free from their web site.
The solution I would personalally use is to buy the SSD and an external USB drive case. Some are plastic, metal and water proof with a simple latched lid that just allows you to “snap” the drive into place.
Remember to remove battery BEFORE doing anything!
Dell Inspiron 1545 Battery Replacement
Take the old drive out, put the old drive in to the external case, install new SSD in laptop and replace battery.
Now boot up from the USB (old) drive. To do so - turn off the laptop, turn it back on, and start tapping F12 key before the Dell logo screen appears to bring up the Boot Menu and select the USB drive and boot up.
Install the cloning software and clone to old drive to the new SSD , shut down, disconnect USB drive and turn the laptop back on. You should boot up perfectly and more quickly into Windows. If you haven’t already done so do an inplace upgrade (keeps data and most programs) to Windows 10 - still free for Windows 7 and above.
While you are at it upgrade RAM (2 x4GB for maximum 8GB total). Also very easy to do on this model:
Dell Inspiron 1545 RAM Replacement
Let us know how it goes.