I had a bunch of files on my dads win98 machine. It would recognize a 128 meg USB flash drive after installing a driver for it. It would not recognize a 1 gig USB flash drive. So I used my digital camera 128 meg card with a card reader. Some examples of a card reader.
http://images.google.com/images?hl=en&source=hp&q=card+reader&gbv=2&aq=f&oq=&aqi=g4g-m6
The driver for the card reader was win98 compatible. Actually, Win98SE (Windows 98 Second Edition).
http://www.lexar.com/au/drivers/index.html#readers
So I had to upgrade dads plain Win98 to Win98SE. If you still have plain Win98 but no Win98SE then try finding a friend/relative that still has one. And you might get by just booting by the win98se disk instead of upgrading. Or buy one off ebay.
http://computers.shop.ebay.com/Operating-Systems-/11226/i.html?Platform=Windows%2520%2528PC%2529&Windows%2520Edition=Windows%252098&_catref=1&_dmpt=US_Software&_fln=1&_ssov=1&_trksid=p3286.c0.m282
Transferring by email. I believe gmail.com by Google limits to 20 megs. And ignore what PCTech said. He must have been drunk and stoned when he answered.
To wrap it up: Win98 Second Edition has USB support. I think it only goes up to 256meg which is impossible to find except on ebay.