So I can install more problems?
I donot see in why you'd want to install more problems, but yeah, that is possible.
You say the total amount of gigabyte the hard drive has is 6.4GB, correct? And now only 1.99GB remains.
Have you ever thought of the fact that the programs and operating system installed require hard drive space as well? Perhaps the hard drives are poorly formatted.
Did you format the hard drive before installing an operating system?
You need to provide us with more adequate information.