Compaq C751 Lap Top     By removing 18 screws on the back, to remove the back COVER, will it expose the hard drive
                                         so it can be removed and replaced?
                          Most laptops have a small access door on the bottom where you remove 1 or 2 screws to gain access to the hard drive but not all do (my Toshiba doesn't).  In that case, it may be necessary to remove the entire bottom panel to be able to replace the drive.  That's not guaranteed either, on an Acer netbook I had, it was necessary to remove it's motherboard in order to access the drive.  I can't say whether removing the bottom will be enough on your Compaq, maybe you could contact Compaq/HP and ask them.

BTW, is that a C751NR?  When I was Googling for info, I saw that model and wasn't sure if it was the same.You Tube video for Compaq Presario F700
How to replace the Hard Drive in your HP Compaq Presario F700
Quote from: strollin on November 07, 2014, 02:20:07 PM

Most laptops have a small access door on the bottom where you remove 1 or 2 screws to gain access to the hard drive

Thank you all for your advice. Replaced HD but could not Install OS Vista.  (Boot MGR Missing) Will try to make Bootable USB Drive