New MB and hard drive... can I reinstall Windows 7?

I'm getting a new motherboard, hard drive, and graphics card today. I want my Windows 7 installation to be on this new hard drive instead of the old one. Am I going to have problems getting it activated? Is there some sort of proper deactivation process I need to do? I heard that your hardware is taken into account for whether it's a legitimate reinstall on the same system... is this true? Are these changes going to make the system "different" to the point that it won't consider it the same computer?

For the record, my old motherboard works, it's just that I'm swapping it out for a new one. I'm putting my old one in my dad's computer. So, if there's something I need to do while the old parts are still in my computer, that is still very doable.

Oh, right, I should have clarified. It's OEM, but I installed it myself. Does that make a difference? I bought the disc at New Egg: Newegg.com - Microsoft Windows 7 Ultimate 64-bit 1-Pack for System Builders - Operating Systems

What's the best option, then? Buying another copy at New Egg, or can I install my current disc and buy another code for the same or less?

Ah well. I'd assumed the low prices on the OEM versions was the way to go, but I guess I've learned I may as well buy the retail box.

If I make upgrades and want to reinstall in the future with a retail copy, can I call Microsoft and get permission to reinstall and reactivate? I guess it'd make it worth the extra cost.