Cannot enable WOL in Ubuntu using ethtool

I'm trying to build a linux box that will run without a monitor or keyboard, runs Ubuntu server, will go into suspend after a certain amount of time and is able to be woken up through network communication. Most of it is already in working order, except for the Wake-on-LAN part.

By the way, my computer is very old (bought it in 2002).

Some relevant info (I hope):

NIC: RTL-8139/8139C/8139C+ (Realtek).

Motherboard: SiS-645 (vendor: Gigabyte Technology Co., Ltd.)

Award BIOS capabilities (according to lshw):

isa pci pnp apm upgrade shadowing cdboot bootselect socketedrom edd int13floppy360 int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb agp ls120boot zipboot netboot

Off course I activated the WakeOnRing/WakeOnLan (as it's called on my Award BIOS) setting, as well as some setting called PME or something.

output from $ sudo ethtool eth0:

Settings for eth0:
    Supported ports: [ TP MII ]
    Supported link modes:   10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
    Supports auto-negotiation: Yes
    Advertised link modes:  10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
    Advertised pause frame use: No
    Advertised auto-negotiation: Yes
    Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                         100baseT/Half 100baseT/Full 
    Link partner advertised pause frame use: No
    Link partner advertised auto-negotiation: Yes
    Speed: 100Mb/s
    Duplex: Full
    Port: MII
    PHYAD: 32
    Transceiver: internal
    Auto-negotiation: on
    Supports Wake-on: pumbg
    Wake-on: d
    Current message level: 0x00000007 (7)
    Link detected: yes

So obviously it's not working because it's on the 'd' setting. So I run the command:

$ sudo ethtool -s eth0 wol g

But with NO effect. I've tried all combinations..

-- EDIT --

Just to be clear: when I run ethtool eth0 after this last command again, the output still says 'd' at "Wake-on". Disabling the WakeOnLan function in the BIOS also has no effect on the situation whatsoever by the way, if that's enlightening in any way.

-- EDIT --

I've tried lots of time, to just wake it up using a magic packet, but (as can be expected with ethtool's output) it's not working.

Here's the eth0-part of the output from $ sudo lshw:

id:           network:1
description:  Ethernet interface
product:      RTL-8139/8139C/8139C+
vendor:       Realtek Semiconductor Co., Ltd.
physical id:  c
bus info:     pci@0000:00:0c.0
logical name: eth0
version:      10
serial:       00:11:22:33:44:55
size:         100MB/s
capacity:     100MB/s
width:        32 bits
clock:        33MHz
capabilities: bus_master ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd
              autonegotiation
configuration:  
    autonegotiation = on
    broadcast       = yes
    driver          = 8139too
    driverversion   = 0.9.28
    duplex          = full
    ip              = 192.168.0.20
    latency         = 32
    link            = yes
    maxlatency      = 64
    mingnt          = 32
    multicast       = yes
    port            = MII
    speed           = 100MB/s
    resources:      irq : 11
                    ioport : e400(size=256)
                    memory : ee003000-ee0030ff

I do not have a cable running from my network card to my motherboard and I don't see any 3-pin connector. I could be wrong though, if anyone with the same card says different I'll be sure to check again.

So, if ANYONE knows how I can solve this problem, or convince me that without a different network card, motherboard or computer I'm pretty much screwed, please tell me!

Thanks in advance.