After weeks of hassle with antispam issues, I've finally accomplished what I set out to do. I now have a secondary, standalone box which handles spam and virus filtering -- with lots of nice options -- and which filters my domains (and is now also filtering a friend's domain for them) -- and which doesn't completely die. My spam levels have been bottoming off with the new system, and I'm very happy, and it already caught and stripped one virus.
In combination with the Webmail system I have for Noderunner, this makes a nice mobile e-mail system. I'm happy with the setup now... yay! I may offer my parents e-mail on the box so they have less spam issues. Hrm.
In addition, I pulled a nasty little trick (temporarily grabbing foobar's IP with another box on the same network) and managed as a result to get the DNS changed over. I've rebuilt the missing domains on ns1.noderunner.net and ns2.noderunner.net, so everyone SHOULD be back online. Whew! I think I'm going to just get foobar shipped back to me rather than dealing with getting it back online again, and I'll copy off anything that anyone's still missing later.