Can I install both Microsoft Internet Explorer 6 SP1 and Firefox and use them alternately? and if so

I have Microsoft Internet Explorer 6 SP1, but sometimes have problems with it - getting disconnected (a window from Microsoft will appear telling me IE has encountered a problem and will have to close), error messages (while trying to connect, something in IE has performed an illegal function and will have to close), problems with scripting, etc. When I have these problems with Microsoft IE, I would like to swithch to Firefox.

Can I install both Microsoft Internet Explorer 6 SP1 and Firefox and use them alternately? and if so, how ?anti virus software

I have 4 different browsers on my computer...no problem. But you will have to choose only one as your default browser. Firefox will prompt you if you want to make it your default.

Can I install both Microsoft Internet Explorer 6 SP1 and Firefox and use them alternately? and if so, how ?aurora

Of course you can

Download Firefox and install it, Windows will create a FireFox Icon on your Desktop, double-click it and... use FireFox !
I have both installed and netscape. I use all three at the sametime! But IE does have its issues so I do use the other two more. (there are some web sites that the features only work in IE) Example: http://snscreations.com/
Perhaps you would be better off getting rid of the viruses and spware causing your IE problems.
Friend,