Well, as I understand it Boot Camp doesn't support Windows 98, so I don't think you'll get any help there from Apple. Supposedly Parallels has support for Windows 98 ( http://discussions.apple.com/thread.jspa?messageID=6146680 ), although I like Fusion more. Did you install the VMWare tools in the Windows 98 VM?
I would check with Fusion's support then, or check if they have forums. I take it you want Windows 98 for some specific reason as opposed to XP?
Something you can also always try is to manually select an audio driver and see if you can get something compatible enough to work. Not sure how well that will work, but it's something to try if you don't want to talk to VMWare.
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