I forget how to do it, but I found a better solution anyway..(Windows file sharing has always been fickle, seems nobody has any idea how to do cross platform/OS file sharing easily.

Install openssh on the tablet through the application manager, then install WinSCP on Windows.

Then depending on the router you can either use the n800's hostname or the IP address (another odd issue which annoys me about routers). Should be the default port 22 unless you changed in.

So..

Address/Server: Tablet's hostname or IP
user: user (or root but I recommend user)
password: whatever password you set if you set one
port: 22 (default unless you change it)

And presto it should work.