Unfortunately it's not as easy for me as I need to track down a bunch of different vBulletin style variables and shit
Rather than doing that (which I know is a pain, I spent ages with StyleVars on one forum and it still looks bad ) you can edit the *.css templates instead. For example, if you wanted to make changes to the CSS for individual posts, you'd edit the postbit.css template.
I'm not particularily fond of this new theme. The dark theme was comfortable and easy on the eyes. This looks brutish, halfbaked, and I don't think it conforms that well with the rest of the website like the old forums.
If it ain't broken, don't fix it. (Well, apparently the spam control was broken, but it's no reason to break everything else too.)
Besides, I don't know how much you know about vBulletin, but they've gone pretty much downhill since they were bought up and the original team left. Were involved with a few scandals, too. I'd stay with what's old and known to be working well.
Ever consider a FOSS alternative? For a website that mainly deals with FOSS software, it's worth a thought. The arch forums use FluxBB (http://fluxbb.org/), which looks like it would fulfill the needed functionality of 99% of the users here.