Ti4200 probs

I have a problem, I installed 98 and XP on my computer after I got the dual boot working. On XP the videocard works fine, but on 98 when I get to the logo screen colours just go all over the place and keep moving, blocks of colour. So, I uninstalled the drivers and used the standard videocard adapter driver and its fine, I tried different versions of the drivers for 98, even different versions of my motherboards drivers and still the same. Anyone know what the problem may be? I've had this card running on 98 before, a few days ago actually. Could it possiblt be the new memory stuffing up? is it possible to reinstall 98 over itself without it deleting XP?

Sorry for the crosspost.