100mbit one way, gbit the other way

Hey
I’m currently running opensuse 11.0 on my fileserver, and windows vista on my main computer, both have gbit lan. I’ve set up samba to connect to the files on the suse box, it all works just fine. Except that when i try to access files on the suse box from my main computer it uses 100 mbit (~12MB/s)and when i copy files to the file server from my main computer, it uses the full speed (~70MB/s)

Any help on what causes this would be much appreciated
Specs:
Main computer:
Asus maximus formula SE
E6850@3.7ghz
4870
4gb ram
2x WD Raptor 150GB@RAID0
vista ultimate 64bit

Server:
Asus P5Q-E
E7200
2gb ram
4TB storage
opensuse 11.0 64 bit

Still hoping someone can help:\