Thanks for the answers.
Now, I fear I have matters worse. Thinking that I would need protection inbetween the uinstallation of Avast Internet Security and the installation of Avast Free, I downloaded and installed the trial of McAfee Antivirus Plus on an impulse. Note that this is all I’ve done so far, I have not yet uinstalled AIS, so the two antivirus programs are running concurrently.
I have since searched a bit however and it appears that the presence of McAfee could potentially cause AIS to uinstall incorrectly, Avast Free to install incorrectly, and when Avast Free has been installed, McAfee to uinstall incorrectly, and I’m wondering how to remedy the situation.
To sum it up: Right now, I have both McAfee AV+ and AIS installed and running at the same time, and I need to get to a point where I only have Avast Free, without the process of getting there endangering my security. I’d appreciate if someone could guide me through this, and preferably quickly, as the AIS trial expires in about a day.