Years ago, you could buy a second hand computer with the hard drive empty, install Windows 98, or Windows ME, and somehow the installation disks had an ample supply of "drivers" to handle activating the modem, audio, and sound card, etc. Those days are behind us. If you buy a second hand Pentium IV, it should have the factory furnished driver reinstall CDs, or you just bought something you probably won't be able to use. The support sites assume that you have these and only furnish updates to the factory install drivers, etc. I bought one such computer a while back and ended up taking it apart for parts because I was unable to locate the drivers I needed anywhere...and I know how to search the net expertly. Finally I bought a second hand Dell Optiplex GX400 because I was able to obtain the factory reinstall CDs. It works perfectly, but without those CDs it would just be more hardware. Hope you profit from this experience of mine.
Harry