My first HDD was a 40MB one which came with my 386SX Acer, circa 1992. It was small even for it's time, and after installing Windows 3.1 and DOS 6.2, less than 20MB were available on the drive.
A couple of months later I upgraded it to a 500MB HDD. It was huge for its time. I remember thinking that I would never be able to fill it up! Eventually I did of course but that HDD holds a special place in my heart, since it was the first computer upgrade I did all by myself.