I want you to go back into msconfig. Go to the Start tab and put the checkmarks back into any that you have removed. Then reboot.That way everything that is listed in Start up will start up and I can better see what all you had previously stopped from starting AND then I can tell you what you should stop and what should not be stopped. It may be that something you have disabled with msconfig is causing the slow down because it should be running...probably not but it is better to check and see.

By turning browsers off I mean they should NOT be open when you run HiJackThis. So if browsers are open, "x" them out so they are closed.

To create a new folder:
Click START > My Computer > Local Disc C: > Program Files
Now, RightClick on an Empty Area and select New > Folder & name it HijackThis and Click ENTER. This is where the HiJackThis program should be located. That way it can automatically make backups so that any fixes done can be "undone" if we don't like the way the computer works.
Once you have done all of the above then run the new HJT scan, save the log as a text file and copy/paste it back in this thread.