Sounds like you have a virus or at the very least spyware.
The pop-ups that you are getting are part of the messaging system and not IE if you are still getting pop-ups with the Google toolbar installed.
To check for viruses, go to
http://housecall.trendmicro.com and then what it can't fix, search on the site for the name and see how to manually fix it.
For spyware stuff, Housecall will find some of it, put otherwise, there are many anti-spyware programs that you can run.
PestPatrol is one that you can run the free version of and it won't remove the items, but you can at least have it tell you what you have and then do a search on how to remove it.
If your computer is running slowly, then right click on the taskbar and select the Task Manager.
Then go to the list of processes running (not the list of tasks, but the actual processes). Make sure that the box is checked to show all processes.
Then list it in order of CPU and memory usage - once you have done that for each of those, you will have a good idea of what is taking up the resources.