Disk - Clean and Clean All with Diskpart Command

Thank you for the welcome, Shawn.

Is the MBR automatically part of the DiskPart wipe, or do I have to specify/alter instructions?

Does this info from Microsoft say otherwise?
A Description of the Diskpart Command-Line Utility

"Diskpart permits certain partition deletion operations that are blocked by the snap-in. For example, you can use Diskpart to delete MBR OEM partitions. However, these partitions often contain files that are important to the platform operation. Diskpart blocks the deletion of the current system, boot, or paging volumes and partitions. Also, Diskpart blocks deletion of the partitions that underlie dynamic disks."

Thanks.

Can anyone help on my related Q:

If both a HD and the motherboard firmware are infected by a trojan virus, does a Bios flash with updates take care of the Mobo?

But which one to do first? It seems that upon format/reinstall, the HD could get infected immediately again by the Mobo, and vice versa for the Mobo.

I'm thinking HD wipe, then Mobo flash, then HD format/reinstall... still not completely foolproof, but does that make sense or not?

This Tom's article, especially the last comment on 2/4/12, are disheartening!
Webroot Discovers BIOS Rootkit

I actually did post it there. Thanks. Here's a wipe/format question, though:

If I use Diskpart or another utility (such as KillDisk or DBAN), is it possible to wipe the HD first but don't format it yet? (Or do all wipes also format?)

Then I would do the format to NTFS later, after flashing Mobo.

While still unformatted, will the HD be un-writable, and thus un-infectable?

It may have been mentioned earlier but you can run the tutorial from the command prompt of a system repair disk if you can't or don't want to boot into the OS.