|While the dun14-95 update will certainly have a file named ndiswan.vxd in it, it won't be the right file for 98.|
Dial-Up Networking 1.4 Upgrade Is Available
Go ahead and get the dun-14 update for 98 or 98se and then just apply the update to let the proper registry entries and file dependencies be created properly.
Or if you can't get the updates, recover the file from your installation disk. For 98se it's in Net9.cab, WinZip will do the trick as well.