...

Have you considered using pscp from http://www.chiark.greenend.org.uk/~sgtatham/putty/ I have found the putty suite to be very useful under windows and doing an scp transfer should get around any possible issues with samba and at least narrow down the possible cause of the problem if it still fails.

On a side note, pscp is god awful slow - feels like half the speed of Linux scp, and of course these are both slower than smb due to the encryption overhead. Useful, sure, but very slow. WinSCP is no better as it uses PuTTY's encryption code.

Still FTP (vsftpd is nice) is an option and one I use on my samba server for big transfers... dunno why, but samba is slow to transfer anything over 1GB is a single file or a collection of smaller files. Mike