1 install operating system, in your case win98
2 install motherboard drivers, you should have a disk for this that came with your motherboard
3 install the rest
Its important to do 1 and 2 before you install something else, after you've done that install your monitor graphics card printer etc, the order makes no difference, the essential bit is to install the motherboard drivers before installing any of the bits and pieces. Incidently the one essential driver to make sure you have before you format is the one for the modem, cos if something doesn't work right you need to be able to get on the net to download drivers or get on the PCA forum for help.