I've been fighting the shared folder/networking problem since the N810 was released. There are many alternative maemo apps that require an IT degree, but none is more easy to use then setting up a HTTP File Server on a windows machine and use Nokia's browser to transfer files.
I like this utility because its simple, has no installation on a windows machine (portable) and the plus side is that HFS works with any internet device regardless of OS because it uses the browser.

http://www.rejetto.com/hfs/?f=intro

I've tried and given up on OpenSSH, winscp, Wizard Mounter, root, xterm, etc, etc, etc
For those that hate command-line, but love their N810, try HFS.