OK,  A couple things

 

Go to MY COMPUTER, then right click C: & select Properties.

 

My 80 GB Maxtor reads as follows:

 

Capacity:  78,937,976,832 bytes   73.5GB

 

Marketing universally defines a GB as 1,000,000,000 bytes. 
 
Unfortunately, Windows defines it as 1,073,741,824 Bytes.  ( hence 78,937,976,832 bytes =  73.5GB)

 

The remaining 1.2 GB or so of space you are "Missing" is the hidden PC Restore partition that will enable you to restore your system to like new status in about 15 minutes using the CNTL+F11 key combination immediately after the Dell Splash Screen at boot (Black Screen with Blue bar across the top)

 

You got your 80 GB drive

Thank you, I thought it would be something to do with the definition of a Gb.

All the best and thanks again, you have been very helpful.

Yes you could have checked the BIOS as well.  In the BIOS it states the hard drive that was installed as is and it said 120 GB hard drive for me.  

 

When I got my 120GB hard drive I saw that it was only reading 113GB.  But then I remembered from my Computer Engineering classes that Windows actually reads 1 GB = 1,024,0000 bytes and stores advertise 1 GB = 1,000,000 bytes.