It seems that myself and a number of other people have run into the problem of Comcast Desktop Doctor making itself pretty hard to remove by not appearing on either the Add/Remove Programs list or the startup services controller found under Control Panel->Administrative Tools->Services. After calling Comcast and being told that if it was able to be removed the usual way I needed to buy a special removal program from the [someone really ought to sue this guys], I poked around and finally found a program that not only automatically removed it, but also kept me from having to manually edit any registry keys. I like to think I'm pretty good at it, but still, if I don't have to risk seriously screwing up the wrong key I don't. So here's what worked for me:
Step 1: Download Free Uninstaller v. 1.1 and extract it to your hard drive. Do not run from temporary file location. It's completely free and can be downloaded here.
Step 2: Run the uninstaller program, right-click "SupportSoft" from the list and select "Uninstall selected applications...". I believe this isn't 100% necessary, but SupportSoft is a comcast diagnostic program that is supposedly dependent on Desktop Doctor. If you want to try and keep it, simply click "Ignore" when it presents an error message later on.
Step 3: Select Desktop Doctor from the list and uninstall it as well. [this is where you would select "ignore" if you wanted to keep SupportSoft].
Step 4: Close the program so that it generates a log of the previous registry values in case you decide to change them back.
Step 5: Enjoy not having to put up with comcast pointlessly using up your RAM!
I hope this was coherent enough. I know it's a simple process, but this is my first time posting a how-to, so please reply with any questions I forget to answer or any advice on how to makes things clearer in future posts. And thanks to all the people whose how-to's have saved my ass in the past!