Installing new Mobo and cpu - keeping old hard drive??

[Vendetta_05]

So I'm putting a new mobo (GIGABYTE|GA-970A-UD3) and cpu (AMD|PH II X4 975) into my old build. I plan on keeping my old hard drives and still running windows 7 64 bit. I assume it would be best to start from scratch and reinstall everything. So I have two questions:

A) is this the best or would things kind of plug and play with the old hard drive?

B) how do I clear my old hard drive? I can't delete system files while its running my current build and I need to have it empty for the start of the next one... does it automatically format when I install windows with the new mobo?

 

[g-unit1111]

A) is this the best or would things kind of plug and play with the old hard drive?

Not sure I understand this question but you can certainly reuse old hard drives - I do that all the time.

B) how do I clear my old hard drive? I can't delete system files while its running my current build and I need to have it empty for the start of the next one... does it automatically format when I install windows with the new mobo?

When you install Windows 7 it will give you the option to do a quick format of your drive when you launch the installation. You want to do a quick because sometimes doing a full format can erase your HD's boot manager.

 

[Vendetta_05]

for A) I mean since I'm still running the same operating system, do I need to reinstall windows or can I run it as-is off my hard drive?