re: installing OpenSuse Linux as the only OS

Is it possible to install OpenSuse 11.3 on a PC that presently has
Windows XP so that the only OS on the PC is OpenSuse 11.3?

Yes indeed. When installing from DVD you can tell the installer to use the entire hard drive.

You might consider installing 11.4, the latest version.

Also make sure you enable the MBR and boot and, if you live in an area that has daylight saving, set the hardware clock to UTC. Linux will than adjust for locale and daylight saving without bothering to change your hardware clock every time.