We've unfortunately always been like that. It seems that just about all of our traffic comes from individual threads that are indexed by google. For example, searching for "wupdater.exe" will result in the second and third links on the search results page being to the wupdater thread. We have quite a few other threads highly indexed by google.
Unfortunately, people browsing for tech support help do a search, click on our site, find what they're looking for, and leave. I don't think they even stop to realize that we're a community, unfortunately.
I tried helping the situation by replacing the Quick Reply area with a message box asking to please register and join our community, but to little avail

I'm desperately in need of help ... I think I'm going to move this thread over to the Web Promotion forum. Maybe people can help me in there??
Incidently, it's the first of the month, which is prime time for many search bots/spiders to be crawling around the www in search of fresh content. We don't have an overwhelming number of bots usually, however.