Backing up Primary Drive in XP

[coldfire]

When I try to back up my primary hard drive on to a DVD-R/RW, I get a reading in My computer, with a right click on the drive, and selecting properties, the pie chart displays, 3.85GB Used. But when I launch Veritas Record Now, and select the entire contents of my primary hard drive, I get a total reading of 2,703.37MB, this is about 1GB of difference. What am I doing wrong, and what is the proper way to back up your entire primary hard drive, so the next time it crashes, I can do a write to hard drive from DVD-ROM and do a faster install.

By the way I do have the system and hidden files set to view, so I should be getting the whole ball of wax.

Thanks in advance for any and all replies.