I had several of them in use under 1.6ish NetBSD, and had problems with them 
initially. First thing, not only under NetBSD but other Operating Systems 
like FreeBSD or Linux is: Disable Plug and Play with the dosbased 
configuration utility you can download from 3Com's website.
Second, depending on your mainboard and its bios implementation you may have 
to fiddle with its bios settings to reserve the IRQ (in your case 10) 
exclusively for the 3com nic. You may also have to choose something like: 
Plug&Play Operating System installed: yes/no enabled/disabled somewhere in 
the bios. Or go the other way around, leave it at plug&play, and try to let 
NetBSD make things right via isa plug&play, but i never did it this way, and 
don't know of anyone having success with this card using this method under 
*BSD or Linux.