We have a TFT and 2 computers (PC/Laptop)
I connect the PC using DVI and the Laptop using VGA and all works fine...
Sure most monitors like mine, have multiple inputs.
The monitor allows you to select the input source, or you can have it on auto and it chooses the active port.
The montors adapts to the graphics cards on both in moments, and if you really like tweaking the monitor, the monitor has profiles, so you can create a setting profile for each PC.
As said, there are hardware switches and splitters, but, why go to the extra expense if its not needed.
Both machines are running xp, so not sure about 98, but monitors are just Plug and Play, and will work in a relative way in anycase.