GoldWave's website does say it's not supported for W98 ...?
GoldWave may actually mean "won't run on Win98," but "not supported" usually just means they won't talk to you about it.
"Win98 is not supported by Microsoft" since a little more than two years ago, but it's still a reasonable choice for some situations.
Since other software makers can no longer pass Win98 questions off and get tech support from Microsoft, they may just be reluctant to try to answer questions about using their software on Win98 - even if suitable components and installations exist.
The GoldWave response in your first post: Tech suport at GW say they've never encountered the problem may reflect the "non-support" situation. They won't know much about what GW5 does on Win98 if they don't talk to people about Win98.
I read your first post as "how do I make GW5 run on Win98," but your comment about your Audigy not being compatible with Win2K or WinXP suggests that you might still be open to migrating to XP. Willie-O, and your use on Win2K at work, both seem to be saying that your Audigy and GW5 would both run if you went to XP; but I'm not sure that you've worked up a warm feeling about doing so.
You've found some roadblocks to an easy installation of GW5 on Win98; but I have'nt seen anything here that I'd take as "it can't be done." The builder doesn't seem inclined to help, so if you want to continue with trying to get GW5 up on Win98 you'll probably have to resort to "User Group" kinds of resources - GW and/or Win98 groups. You may end up going back to the GW people to get the appropriate components; but you may have to find out what to look for by doing some brain-picking elsewhere.
Your original "reboot" problem does suggest one of the virus plagues, or a "resource" problem. If you haven't done so, you do need to hook up with one of the AV sites and get a good, current, scan. If it's a resource problem, you might be able to get some useful information by turning on the "Resource Meter" and/or "System Monitor" that you can find in your Win98 Start-Programs-Accessories-System Tools area, to see if something unexpected happens when you try to run GW; but of course you have to watch the meters to find out anything - and then figure out whether it means something.
If you're seriously interested in facing up to WinXP, I'd say that your 256MB RAM is adequate (but I'd recommend more, eventually). It should be enough to run fairly well on a standalone machine. Having "quite a lot of hard drive space" means rather different things for Win98 and for Win2K/XP. A minimum install of either 2K or XP, with basic Office and a few decent applications needs at least 20GB on the (bootable) hard drive for acceptable performance (IMO). You should check to be sure whether you have a PIII or PIV compatible processor, and verify that meets the published requirements for XP (There's a minimum speed spec too).
I run Win2K on a machine with 256MB RAM and a 20GB C:\ drive. Performance is in the "generally ok" category, but isn't really up to what it should be. I would NOT recommend Win2K for most users - WinXP is the more suitable one, unless your local sysadmin tells you you need 2K. (If you don't have a local sysadmin - use XP.)
I run WinXP on a machine with 1024MB RAM and a 120GB C:\ drive. I could get by with a little less, maybe; but I certainly wouldn't buy a new machine with anything smaller. I have considered, seriously, converting the Win2K machine to XP, and wouldn't worry too much about it running well with the present resources, although I'd probably kick the RAM at least to 512MB "on principle."
Each of these two machines has an external USB 120GB hard drive attached, because both machines were getting crowded for disk space. (It did take about 2 years use on the Win2K machine to reach the "constipated hard drive" condition.) From the XP, I can access both C:\ drives and both external hard drives via my workgroup LAN. The Win2K machine does not have "sufficient resources" to access the external drive attached to the XP machine. This isn't something that would be significant to most users, but does indicate that the 20GB boot drive and 256MB RAM are pretty well "used up" by Win2K, and the situation would be similar with XP on the same machine.
I do have one surviving Win98 machine, that screams along (well, whines politely) with 256MB RAM and four 2GB partitions, but that machine would not survive a newer OS. It's a Pentium from before they had numbers, and a sand-dial in place of a clock. (And does anybody want to buy a laptop that couldn't upgrade from Win95 to Win98?)