Motherboard replacement with Vista

I have this Gateway computer that came preassembled as I could save money on it at the time. I have since replaced the ram, case, power supply, and graphics card so only the motherboard, cpu, and hard drive remain. I like the hard drive, but it has Vista premium 64 bit on it which came with the computer. I was wondering if I could replace my motherboard and still use my existing hard drive with it. Would it boot? Would I need to hassle with microsoft activation or what? I have seen mixed results for Xp, but I'm not sure what the deal is with Vista as of yet. The computer came with a cd, but I'm not sure if it would even install without recognizing the Gateway motherboard.

edit: I probably should tell the hardware. The hard drive is a 640gb Western Digital, the motherboard to be replaced is a Gateway AM2 with a x16 slot (sorry no model #), and the the motherboard to replace with is a
ASUS M4A78-E Motherboard.

You need to uninstall, or change to generic, all hardware drivers, then shut down.

install the new motherboard.

boot from your vista CD, and do a REPAIR install.

Plenty of references on the web.

Google: "change motherboards without reinstalling windows"