Hey everyone, I am about to upgrade my computer to a 64-bit Intel Q6600. I am curious, when I upgrade my computer to 64-bit hardware, will I be able to upgrade install to the 64 bit version of Windows? ( Without clean installing it) Thanks in advance.

No, you cannot upgrade from x86 to x64 with any version of Windows. You will always have to perform a clean install.

No, you cannot upgrade from x86 to x64 with any version of Windows. You will always have to perform a clean install.

Even if I boot from the DVD? With the 64-bit hardware installed? And my data coped to another hard-drive?

No, you cannot upgrade from x86 to x64 with any version of Windows. You will always have to perform a clean install.

Even if I boot from the DVD? With the 64-bit hardware installed? And my data coped to another hard-drive?

Yes, even if you do everything like you would in x86. It is simply not possible to upgrade from x86 to x64, as they're not the same OS (especially with XP - XP x64 is really Server 2003 under the covers). It's documented lots of places, but the most direct is here:

Whatever version of Windows XP Professional x64 Edition you use, however, it will only be available as a fresh install. There is no provision for an upgrade from Windows XP Professional.

Note that this applies for Server 2003 and Server 2008, Vista, and will apply for Windows 7 too.

No, you cannot upgrade from x86 to x64 with any version of Windows. You will always have to perform a clean install.

Even if I boot from the DVD? With the 64-bit hardware installed? And my data coped to another hard-drive?

That wouldnt be an upgrade that would be a clean install still. Basically whats going to happen if you boot from the dvd, its going to roll your old install into a folder call windows.old. All the apps and programs wouldnt be installed already. Keep in mind you can do this with an upgrade dvd or full dvd.