I finally got my Pi. The last days I tried a lot of MediaCenter-Distros and yesterday I decided to stay with OpenElec since it seems to be the fastest. Without any further configurations OpenElec seems to have enabled samba and even already shared my usb-stick in the Pi. I am able to send data from my Win8-Computer to the usb-stick on my Pi. But this process is pretty slow. I read a lot that this is kind of normal but I try to get as much speed as possible. So I first switched from WLAN to LAN on the Pi, so that the usb doesn't have to share its power. Then I formatted the usb-stick from NTFS to ext4. Still pretty slow. The last thing I can think of is the samba-encryption. Some people say that you can disable the encryption to get a little speed boost. I want to try that too but I have no idea how. I don't even know yet how to open a terminal, since until everything was kind of out-of-the-box in the options of OpenElec. Thank you in advance!
I only get 3-4 MB/s transferring data to the pi (B or B+) over ethernet using ssl encryption, even though writing directly to an attached drive is much faster than that (40-45 MB/s). Max throughput on the USB 2.0 bus (which includes the ethernet jack) would be 60 MB/s (i.e., it would be impossible to transfer over ethernet to an attached drive faster than 30 MB/s).
I don't do a lot of GB magnitude transfers (when I do, it is easier to just connect the drive to something else) so I have never been bothered enough to diagnose this. Quick test of an unencrypted transfer looked to be more like 8-10 MB/s, which is still slow.
According to this, you would forbid encryption with samba by setting:
smb encrypt = disabled
/etc/samba/smb.conf (presuming that is the correct path on openELEC). Probably you then have to restart the server.
Keep in mind it may be the windows box enforcing encryption, so you may have to reconfigure something there too.