Soekris Net4801 performance

[johnryan_852 at iprimus.com.au]

Hi, I've just bought 2 soekris net4801-60 boxes and am having trouble getting
them to perform under FreeBSD.

They are on a 100Mbit network and the network works fine for other machines
- FreeBSD, Linux and Windows.

I've tried a custom kernel running FreeBSD 6.1 PRELEASE and a GENERIC kernel
running FreeBSD 6.0 RELEASE.
Custom kernel has
options         CPU_GEODE 

ftp put is around 3Mbytes/sec and ftp get is around 2Mbytes/sec
ifconfig says:
sis0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        options=8<VLAN_MTU>
        inet 172.20.36.56 netmask 0xfffff800 broadcast 172.20.39.255
        inet6 fe80::200:24ff:fec5:cf48%sis0 prefixlen 64 scopeid 0x1
        ether 00:00:24:c5:cf:48
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active

Has anyone got any experience with these machines and any advice?

Thanks in advance
John Ryan