|Can the machine boot from a bootable cd???|
"Could I use antivirus from a CD to get rid of this thing?" yes but you need to be able to boot from the cd.
all of these require you be able to boot from the cd drive.
if you can boot from the cd you can just use this to get your data
if you can't boot from the cd, you can create a puppy boot floppy on another machine and use it to boot from and run the puppy cd on your machine.
you can also pull the drive out & put it in a another computer, either externally or internally but, this is not something I perfer to do with a potentially infected drive.
"I know that it is a virus because its previous owner told me so and all evidence points to a boot sector virus."
I think it is just as likely the drive is toast, which means you will never get the data off.
"Problem is that I can't access directories of the hard drive, because it tells me -
Not ready reading drive c:"
is the drive recognized in the bios?? if not it may to bad and won't be recognized by any software you try.