I've got Alpha 1 installed on this model of computer, as it's the only one I have to spare and Haiku boots on (it fails on my laptop... perhaps I should send a bug report?).
I cannot get any network connection at all on the computer, and it currently has a Realtek 8139 ethernet card. I'm not sure if this particular type of hardware is just not supported or what. As far as I can tell, Haiku already contains a driver built-in for the card, but the Network preferences application just doesn't list the device (although listdev does).
As I currently have Arch Linux also on the disk, I'll output "lspci -vv" from that for the ethernet card:
02:0f.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
Subsystem: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 66 (8000ns min, 16000ns max)
Interrupt: pin A routed to IRQ 19
Region 0: I/O ports at 1000 [size=256]
Region 1: Memory at 40000000 (32-bit, non-prefetchable) [size=256]
Capabilities: [50] Power Management version 2
Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=375mA PME(D0-,D1+,D2+,D3hot+,D3cold+)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Kernel driver in use: 8139too
Kernel modules: 8139too, 8139cp
Also just to demonstrate that the card itself is functional, "ifconfig eth0" from GNU/Linux:
# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:90:47:03:92:4A
inet addr:192.168.1.40 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: 2002:62ed:d374:beef:290:47ff:fe03:924a/64 Scope:Global
inet6 addr: fe80::290:47ff:fe03:924a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1024636 errors:0 dropped:0 overruns:0 frame:0
TX packets:832107 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:901340753 (859.5 Mb) TX bytes:448648040 (427.8 Mb)
Interrupt:19 Base address:0xc000