It's hard to say, unless you know exactly what IE10 installs and changes, and what IE9 does above and beyond IE8 on a Win7 system. I know where that information can be gathered, but that's not something the layperson is going to be able to find. In situations like these, I usually make a restore point before downgrading and revert if anything goes horribly wrong. If you don't have that, it's probably best to start over.
Thank you very much for your help. As you correctly pointed out, this is unfortunately IE. Had it been a normal update I suspect it would have been easier, but with IE it's all of the non-COMPONENTS etc. hive stuff which concerns me. Even looking through the manifests and update XML to find most of it (although that would be a tremendous amount of work

), I still wouldn't be able to get all of it by any means. And anyway, contemplating solutions which take longer than a Clean Install, regardless of their chance of success, is silly
I might try a Repair Install, but it's such a hassle. Even if I slipstream an SP1 disk (or uninstall SP1), I'd have to move all of my documents folders, etc. back onto my SSD (I think that's necessary???). But they won't fit, so then I'll have to back them all up, and delete the contents before restoring location.
Unfortunately, I had no System Restore points. I hadn't noticed, but my system restore points were going onto my SSD where there wasn't enough space and they all got deleted
lol, TBH, I think a Clean Install's the way forward. After all, they don't take that long and they come with lots of other benefits for problems jury rigged solutions only compound.
Thanks again for your help :)
Richard