Hmm. Could be an issue of Windows 98 and your older system's motherboard not supporting USB 2.0.
Maxtor was bought by Seagate. Here's their Support site, with a listing of "All Products" with 3100 in their name.http://www.seagate.com/www/en-us/products/product_finder/?sourcePage=0&locale=en-US
Everything here is either an internal SATA drive, an eSATA, or USB2.0
Here's a link to the troubleshooting thing for one of their USB2.0 drives not being viewable on Windows 98/MEhttp://www.seagate.com/ww/v/index.jsp?locale=en-US&name=win98-devman&vgnextoid=2bba37ff660b3110VgnVCM100000f5ee0a0aRCRD
Link to help find the right drivers for Windows 98/ME. Scroll down a ways and there are two links. One for current products, and one for older "legacy" products.http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=201413