Are still here.
For an awful example of the rubbish that can accumulate on an unprotected system, and (unlike myself) a guy who really knows what he's doing when it comes to cleaning up the mess, have a look at Tech Support Guy. In the Horrible Example, sachost.exe was just one of the many problems he managed to clean up.
Meanwhile, the major anti-virus vendors still don't have it on their scopes. But as the result of a kind reader giving me details on GriSoft's AVG Free Virus-Scanner, I now have another line-of-defence installed. No, it didn't detect sachost.exe, but neither did any of the others. And the price was right. Being a less-than-trusting-soul, I did a Google search on "AVG", just in case it was malware, before I even thought about installing it. Having checked its bona fides, the installation of the latest version was relatively straightforward, and the scanning time was comparable to PC-Cillin's Housecall. It's too early for me to recommend it, but after giving it a trial for a few months, I'll see how it goes.
[Thanks to reader Alan Murdoch for the data on AVG]