Quite a few things can cause this.
See 48bitlba at:
http://www.48bitlba.com/

                                        Rick Glazier

From: "Harvey Rose"
>I bought a new computer that has a 250G drive - Western Digitial SATA. 
> When I run the system information from Windows XP it shows only 137G 
> available. It is formatted in NTFS. The model is WD2500AAKS. They put 
> Windows XP on for me. I have installed my programs starting to transfer 
> files from my old hard drive okay but started run to out of space(Also 
> putting new programs on). Is the operating system Windows XP Home 
> edition reporting the wrong space or did they format it to this limit?
> 
> Harvey Rose

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