Yes, some viruses can affect the hardware. One even killed your BIOS, rendering your computer unbootable. Boot Sector Virus? Wipe your Master Boot Record, and the damage is gone. The Boot Sector (or MBR for that matter) are not hardware. They're a section of the hard drive.
http://en.wikipedia.org/wiki/Boot_sector
http://en.wikipedia.org/wiki/Master_boot_record

That's what I like about Macs. :cheesy:

although it made your computer unbootable , it can't infect your hardware. All you need to do is re-installing you OS and fomating your hardware and then everthing is ok. so did the MBR Virus.