Hamrah
If you can see the BIOS loading then your video card shouldn't be causing any problems in DOS mode, as they work on same resolution.
I guess something with DOSS is wrong - but then how could win98 work with faulty DOS??
..................walks away scratching head
all I can think is to go through config.sys, autoexec.bat and dosstart.bat and look for anything unusual and try setting CMOS to default, could also try re-installing win98
*install Linux* (yeah I know, it doesnt help....)