Red Squirrel,
I am using a C2D era laptop w/ 2.5 gigs of ram with a slow 5400 rpm disk, as we speak. You'd be surprised, how well Vista runs here. What you describe of course is unacceptable, not sure what's wrong with your box. Vista SP2 is on par with 7 SP1 in my own experience, and in some ways I like it more (more aggressive prefetch mechanism, for one).
If anything, I'd upgrade it to 8.1 or 10, nothing less. And it isn't like I am used to using slow things. This thing when configured properly runs well enough. Vista is disk intensive, just like anything newer than XP SP3 (after a while it gets better, though). I have three spare SSDs on hand, you can imagine that if I am content with the performance here with a slow mobile hard drive, then it must be good enough. Of course, I am not doing anything disk intensive here anyway (like editing videos for example or booting/shutting down all the time), just light browsing and watching YouTube <=720p videos. For anything more cpu/disk intensive, this thing would prolly annoy me to hell. Well, I have a different computer for that purpose. By the way, I have exactly the same laptop w/ Windows 10 on it, and while it is faster, no question about that; Windows 10 still won't play 1080p videos smooth enough either, so why bother. So people not willing to upgrade, I can understand that.
NB.