Been a long time since I tried it. It was pretty good, at the time of its release possibly the only free resident antispy.
In some ways superior to Spybot, in many ways probably not superior to Superantispyware.
One of those ways was what I perceived to be the developers prioritizing of the toolbar marketing at the expense of the program quality.
(The toolbar is Crawler's, installed under the marketing guise of "Web Security Guard", a kind of browser add-on a bit like SiteAdvisor. Nothing wrong with it if you don't mind toolbars, however.)
I uninstalled it some time ago. There have been a number of updates since then. If the configuration hasn't changed, installation of the Clam AV and WSG components is totally optional. I've used the Clam in the past, didn't conflict with Avast. But IMO it's not necessary, and I don't recommend it (the integrated AV, that is.)
Try the program out. Be advised that if you activate the HIPS feature, you'll need to learn how to answer popups about the innermost workings of Windows. Not a bad learning to undertake.
The forum is helpful. There are quite a few experienced and knowledgeable users, some hangers on, and a few wannabes.