As I said, try that generic driver I attached. I've personally used it many times and it has supported every USB drive I've thrown at my old computers.
You were correct, the Win98 driver worked. Maybe I made a wrong assumption or Win98 works a bit differently than I remember and what I'm familiar with now, but I installed the application in a new directory and thought that was all I needed. It wasn't until I went into the Device Manager and pointed the unknown USB device to the directory that it installed the driver.
Just for my understanding, and anyone else who decides to use this driver, I noticed a few anomalies. The USB thumb drive is labeled 4GB_USB, but in Win98 Explorer, it showed the USB in lower case. Also, I 'ejected' the drive, however, it was still showing in Explorer. If I attempted to click on it, I'd get an error saying not found (or something to that nature).
Are these faults of Win98 or a few hiccups in the driver? Either way, if these are my biggest USB problems, I'll be quite happy to work around them.

Having experienced these 'hiccups', I"m wondering if I needed to do something with CutePDF, such as 'adding' it as a printer because it wasn't a device option when I attempted to print something; and then I uninstalled CutePDF.
I'll need to either try it again or send an email to the company asking which version(s) support Win98; and ask if their 'evaluation' version will need to be purchased.
On a side note, I don't know if this oscilloscope can be upgraded to XP. From what I understand, I have a model 54831 with an 'M' at the end. The 'M' means it was a military unit, and a military unit can't be upgraded unless the motherboard is replaced.
Either way, I'm not necessarily afraid to tinker with the software, but I went through some work to get the software running and afraid I'll dig myself into a hole trying to upgrade. When I first purchased the scope, the scope booted just fine. Suddenly I got an error and the HP community thought it was something in BIOS. I kept tinkering with settings in BIOS, then it was assumed the power supply was bad. After probably a month, I stripped the entire thing down to just the motherboard to eliminate any possibilities. In any case, I discovered the mSATA drive that the previous owner installed crashed (or the OS became corrupt). He sent the drive image he had, and Windows booted, but the scope software failed to initialize the scope (normal boot sequence is an Agilent logo covering the entire desktop, and, after about twenty-seconds, the relays click and the screen changes to the oscilloscope). Someone else sent their image and I had a similar experience.
Finally after about three or four drive images (comprised of both Win98 and the scope software), I managed to get one that was bare bones and worked. Unfortunately this also meant it had calibration and self-test data from the scope it came from. Due to the scope having issues in channel 2 and 3, I was unable to calibrate any channel thus making the good channels (and bad channels when used in the only states that weren't broken) to have incorrect measurements.
After discovering a few poorly replaced components, incorrect value components that were installed by a previous owner, and replacing two hybrids (one in each of the bad channels), I finally got the scope working and was able to calibrate it.
Having said all this, I haven't found an actual installation CD for just the scope software, meaning, I can't install Win98, and then install the scope software. This makes trying to upgrade to XP difficult, and most people I've found have upgraded to Win10 which requires the motherboard upgraded. While they are at it, they replace the screen with a higher resolution version.
Performing all these upgrades would certainly be nice, it's an old scope, and I feel due to obsolete parts, dumping too much cash into upgrades is more of a gamble.