Good luck Cyber, you can upgrade from a 32x OS to a 64X OS, I did just that after upgrading my MB, CPU, and RAM. This was an upgrade from XP Pro 32x to 64x Win 7 Home Prem SP1. XP was on the HDD, I upgraded the MB and CPU to 64x capable and added RAM. Purchased the Win 7 upgrade cd (it had both 32 and 64 cd's) and since my system was now 64x that's the disc I used to upgrade from XP to 7.
I've now gone to an SSD (actually I'm on the 2nd one in this box, 1st was 64G, now have a 120G) and found the simplest way to move my Win7 OS was to install the new SSD, boot from the 7 cd and use my backup image to put the OS on the SSD.
That's the system and OS I used to upgrade to W10, so far everything's ok.
PS you can't upgrade the same OS on the same box from 32x to 64x, in that case you must clean install the 64x.
Nearly all the problems I had, were self inflicted by me, so I'd like to Thank Bob and others for helping me out.
For Starters I had no idea that my Processor was 64 Bit (how crazy is that)
What threw me was my XP Pro 32 Bit that wouldn't let me upgrade to Windows 7 64 Bit until I discovered the magic of banging a copy of Windows 7 64 Bit straight on there, by doing a clean Install.
Then having done that the Edge Browser would only open for about Two Seconds, after which it just fell off the Screen and so I had to do a clean Install all over again.
It seemed to take forever and was up to 3 AM as I needed a New Sound Driver and had to stop my Graphics Card updating drivers which made the System Crash.
But Touch Wood, it seems to be working OK at the moment.
Spoke too soon the Mouse keeps freezing up! and the Scrolling seems a bit glitchy.