I dunno, my vista PC has never blue screened at all. Only a few times when dust had amassed in the CPU fan a few years back did I have a few bluescreens, but clearing the dust completely solved that issue. The bluescreeen I've recently had was clearly related to my GPU which was fried, so that makes sense. I've never experienced any slowness on my system, not even now, after eight years of use (I do make a point of it to update my drivers every once in a while and run various anti-malware tools every now and again), so switching to windows 7 seems like a lot of hassle for a system that has never given me problems before. Of course, I couldn't say how much faster it would run on Windows 7 because I've never experienced it.
Like I said, I've lost my license for Windows 7 from my old laptop, and pirating a whole operating system feels like something I could potentially mess up. I might ask some family members if they have old Windows 7 licenses lying around they're not using.
I liked how Windows 7 and Windows 8 let me upgrade to Windows 10 without losing any of my shit, but I presume upgrading Vista to 7 will not be so seamless? Of course I can make back-ups of everything I use and move all my installers, paperwork, photos, music, savegames, mods and downloads to my external hard drives but I don't like hassle.