2007 is old these days? I think that's when my netbook I bought refurbished is from originally, and I never had an issue running Slackware 14.2 on it, without even bothering to figure out anything to tweak. I'm still salty that Linus went and made the kernel too beefy to run on 286's. I'm sure this is useful to someone out there, but have to wonder how on earth you can showcase Linux on old hardware without even mentioning Slackware. It seems almost downright disrespectful. The only choke point I'd assume you might run into would be with full weight modern browsers, but if you can be content to run something like Midori or Surf you're golden.
I recently repurposed an old Win XP machine (Athlon 64 X2, circa 2010) that had been sitting unused for 15+ years. I threw in 4Gb of memory and a pci wifi card and installed Lubuntu. Works great! FF is a bit sluggish on it, but I don't care, because it's primarily a file server.