I am about to rebuild my main general purpose PC which is kindly donating its existing parts to a HTPC. I use the GP PC for everything from Sage to gaming. One of its main purposes will be encoding video and audio material to put into a NAS based media library which will be accessed by MCE machines. I wanted to keep this task of the HTPC itself because it is already going to be busy enough being a PVR and DVD player etc. This machine has been in service a long time and is probably on its third major hardware upgrade. Parts of the setup go back to 98/ME. As you might expect, its now bloated with redundant software, orphaned dll's and is getting ever "quirkier" in operation. However, the thought of doing a clean install and having to identify the useful software and reload it all has never been that attractive. What I would like to do is to start afresh but using XP 64 as a base. This is to make best use of the new Athlon XP64 chip (and an XP64X2 later) and its better performance on jobs like encoding. I am not confident that everything will work on XP64 yet, so I want to keep the existing 32bit installation. When I have everything up and running I might remove the existing 32bit installation and do a clean install, probably using MCE. I haven't done dual boot before so I have a few questions: Will XP64 have its own independent registry? Do I have to reinstall the software I want to use whilst logged into XP64 before I can use it in XP64? If so, can I reinstall the software into the same folders or will I have a duplicate set of "Program Files"?