|Sorry for disappearing, but I was sat here ready to go when I posted that and hoped for a fairly quick response because I didn't want to start if I wasn't going to be able to activate it using the same key (since I'd already activated using the 32bit version). And since my frantic Googling didn't seem to be yielding particularly clear answers. After an hour I finally Googled across my answer so I went ahead, then in the moment of reinstalling I totally forgot I posted this.|
I see the topic kind of snowballed after someone automatically assumed I was doing this on a Mac based on my system spec, sorry about that but I didn't notice that's what it said, in fact I don't actually ever remember writing it down as just "Macintosh", I'm fairly sure I used to have it saying that I had multiple systems, two PC's running Windows 7 and a few Macs running either OS X 10.4, 10.5 between them.
As it happens this question was pertaining to a PC, I already knew my computer could run 64bit OS, I built it that way. The problem was when I came to install WIndows 7 on it originally a few years back I decided to stick with 32bit since at the time 64bit would have held no benefit to me. So I installed and activated it on 32bit. It just happened that when I went to reinstall last week for the first time in years I realised I can actually benefit from having a 64bit OS now, but I just didn't know if since I'd already activated the licence once on the 32bit version if Microsoft allowed it to be reactivated on the 64bit version.
It does, needless to say. But anyway thanks for the responses. I'm sure this will be useful to someone else if in time.