I also had same kind of problem!
After you ENABLE you LAN card,look at the back panel of your CPU where the LAN cable is plugged in.It must show a fluoroscent green light(or some other color).If you can see that light then do the below steps:
Open RUN dialog and type cmd,hit enter
In Command prompt type ipconfig,press enter.If firewall alerts u that ipconfiguration utilitity wants access,ALLOW acess
Some configuration willl be displayed as shown in screenshot below
screenshot: *i6.tinypic.com/241rv53.jpg
The value i have highlifghted in green box is your gateway.
Lets say that your gateway is 192.168.21.3
then type ping 192.168.21.3 -t and hit enter.
If you get continuously something like
Reply from 192.168.21.3 bytes=32 time=x ms TTL=225
it meams ur LAN is working properly.
If you get Request timed out,then check beck panel to see if there is an FLICKERING ORANGE light.
IF orange flickering light present=LAN card is proper.
If NO orange light=LAN problem
So problem is with either LAN card or LAN cable.
You mentioned that on your friend's cable it was working,So it means,YOUR CABLE IS DEFECTIVE.
Ask your LAN incharge to get the NETWORK CABLE TESTER TOOL(they already have it with them).And one more thing,Even if the tool shows that cable is intact,still there are chances that wire is defective.
Also before you try to change your LAN cable,ask ther LAN incharge to CROSS-CRIMP your cable at Hub as well as at your end!It is most probable that 1 or more out of 8 wires habe a break in them!