LAN bandwidth in Linux is low

everyone, I connect two PCs both with 1000Mbps NIC. One(A) of them runs Fedora 8 while another(B) runs Windows7. I test bandwidth between them with Ixchariot, it shows about 10Mbps. If A and B both run Windows7, I run Ixchariot again and it shows about 1000Mbps. I transmit file from B to A(Fedora 8) and the speed is about 10Mbps. Why are the bandwidth under two tests different?

The follows are outputs from ifconfig and ethtool:

[root@Dom1 ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:24:1D:50:B9:C0  
          inet addr:192.168.1.101  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::224:1dff:fe50:b9c0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:290214 errors:0 dropped:889731948 overruns:0 frame:0
          TX packets:579263 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:19165638 (18.2 MiB)  TX bytes:875177493 (834.6 MiB)
          Interrupt:17 Base address:0xc000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:4932 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4932 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:5011460 (4.7 MiB)  TX bytes:5011460 (4.7 MiB)

[root@Dom1 ~]# ethtool -S eth0
NIC statistics:
     tx_packets: 816440
     rx_packets: 409104
     tx_errors: 0
     rx_errors: 0
     rx_missed: 0
     align_errors: 0
     tx_single_collisions: 0
     tx_multi_collisions: 0
     unicast: 408962
     broadcast: 38
     multicast: 142
     tx_aborted: 0
     tx_underrun: 0

[root@Dom1 ~]# ethtool eth0
Settings for eth0:
        Supported ports: [ FIBRE ]
        Supported link modes:   1000baseT/Full 
        Supports auto-negotiation: Yes
        Advertised link modes:  Not reported
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: FIBRE
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: pumbg
        Wake-on: g
        Current message level: 0x00000033 (51)
        Link detected: yes

[root@Dom1 ~]# ethtool -i eth0
driver: r8169
version: 2.2LK-NAPI
firmware-version: 
bus-info: 0000:03:00.0

You do have a problem with either your NIC or driver. ifconfig reports that RX packets:290214 errors:0 dropped:889731948 overruns:0 frame:0 so almost 900,00,000 packets have been dropped and only 300,000 received! That is huged!

Try investigating logs (/var/log/messages and the output of dmesg).