You can not access the BIOS via a mouse. You will need to plug in a keyboard that the computer recognizes via USB or PS/2. You may of course leave the wireless still in. The computer will be able to use multiple input devices so long as all the necessary drivers are installed.
Hey, thanks for all the replies. I had neglected to mention, but I had tried the corded keyboard and the battery replacements, etc, but nothing worked. Finally, I was able tonight to get the keyboard to respond and found the real culprit. The previous owner had partitioned the 80gb HD into 20gb and 60gb partitions, the OS being installed on the 20gb and that partition, for some reason, named drive "D:". Bottom line is that drive D got quickly filled up beyond its ability to function normally. I believe that was the problem. I'm now trying to unload drive D to give it breathing room. Thanks again.