Why not use very popular Oracle VirtualBox?
Because neither virtualbox nor virtualmachine runs windows98,at least not to a usable degree.
Anybody who want's a somewhat decent windows98 emulation has to run VirtualPC wich only runs on windows xp(it runs on win7 as well but you have to rename the installation and afterwards the exe otherwise windows blocks it) ,VirtualPC emulates hardware that is old enough for windows98 to recognize and to use it.
Look on the interwebs for digiex premade windows 98 since it already comes with all the necessary drivers.