Bill, it may not even be you. The net has been acting strange ever since these latest rounds of worms have gotten released. My ISP sent out a letter a couple weeks back (in response to all the complaints) stating that many servers are still overloaded due to alot of peeps still being infected and not knowing it. I also suspect some of the critical updates for IE and XP. I remember a huge problem that SP1 would cause systems slowdowns, so I never installed it.
I have experienced many of the same symptoms you describe and I am on cable. It seems to clear up and be fine, then gets wacky every now and then.
There is no pleasure in having nothing to do; the fun is having lots to do and not doing it.