Poor Incoming Network Performance from Mac Mini

Question

I have a 1.5 Core Solo Intel mac mini running Leopard 10.5.4. I currently have it connected directly via patch cable to a eMachines wintel running Windows Server 2k3 that I'm using for a server. The weirdness comes in whenever I'm trying to transfer files back and forth across the Ethernet connection. Both Ethernet cards are manually set to 100mbit full-duplex.
I have enabled SMB sharing on both machines, and I have the FTP server setup on my mac mini. Below are the speeds on which I'm getting file transfers:
SMB:
Mini -> 2k3: 8MB/sec
2k3 -> Mini: 3MB/sec
FTP:
Mini -> 2k3: 11MB/sec
2k3 -> Mini: 3MB/sec
I've tried disabling IPv6 on the Ethernet port in the mac mini. The firewall is turned off. And surely the stock hard drive in the mac mini can write faster than 3MB/sec. Does anyone have any ideas on what could be causing this insane slowdown on incoming file transfers? I've looked through the forums for any possible fixes and have come up blank.
Thanks in advance,
Josh Hogan

Answer 1

@ SilverSkyRat: Permission were all correct, but no connection login as a network user. Thank you for your input
@ BDAqua: You are right. Thank you also
I received the this link from Apple regarding my connectivity issue: http://support.apple.com/kb/HT4945?viewlocale=en_US&locale=en_US
However, I found a simple solution to over come my problem: here is how I did it:
1- I created a Network user jsmith using Server App with password as "password"
2- Then went to System Preferences\Users & Groups\ and create a standard user account as jsmith with the same password as "password"
Then I was able to map my network drive that resides on the Mac mini server to a Windows XP machine. Both password of jsmith has to be the same in order for the mapping to take place.
This solution resolved my connectivity issue. However, there is one thing I do not like about it:
1- I have to make sure that when a user changes his/her network password, I have to change his/her password at the server...it is double the work
2- Everytime I create a Network User Account, I have to create the same account on the local server with the same password.
Thnak you All for your input
-AN