Seems I got SMB-Handler working now with Linux. At least I can read and write files, and it doesn't seem awfully slow either (the linux machine is on wireless at the moment, which kind of limits the speed ).

I think the problem before was that I had set a user name, when in fact I wanted to log in as an anonymous user (= no user name, apparently).

Anyway, if someone else needs help with this, please feel free to pm me and I'll start on a simple step-by-step guide.