would be better if OP can tell us what kind of computer being used (name & model of PC) and what kind of drive that person is installing Win7 onto (either an HDD or SSD)
In that sense, HDD0 = boot disk. Could be an SSD, too (unless it's IDE). With BIOS protection of MBR/boot record on, the BIOS would display a message on access, but only in the real text modes. In graphics modes there is no message, only a silent block. There are also AV software and security programs doing that.