orangebrightbox router / computer

hi we had fire optic installed in aug this year it was running like a dream untill 3 days agao , i phoned my isp and they tested out the router etc , we have got 3 computers 2 desktop and a laptop the speed is ok my my wifes computer and on the laptop , but on my computer the speed is around 8 mbps and i am on 40mbps so why am i running slow my isp have said that it is my computer , after all the test where done like change over router ,changed cables etc but still my computer internet speed is very slow is there any way of testing the hard ware to see if there is a problem , i know there is but unsure what it is and why thanks

thanks for your reply the computer is wired connection , both desktops are wired but laptop is wireless so we dont understand why my desktop computer is running on the internet like a snail and yet the others are running faster thanks

tthank you for your replys the elthernet cable is 3ft the router is the same distance from my computer but this slow issue has only been for the past 3 days , we have updated all drivers not tried safe mode yet , when we spoke to orange today they done all tests on 3 computers and they said that it was my computer which was the problem as we changed router and cables , updated drivers , still slow on my system i should be getting 40mbps instead i am getting between 8 and 13 mbps , would it be a problem with network card ? i can connect but does go like a snail and yet the other 2 computers are fine with speed ..
i am not sure what you mean by this eg: What speed is the network adaptor in your computer running at? the router is a orange brightbox that they sent me when the fibre optic was install in aug this year
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Users\gizmo>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : gizmo-PC
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : default

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : default
Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller
Physical Address. . . . . . . . . : 00-1D-92-84-E9-C7
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::480c:c78b:1500:b24%13(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.57(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : 01 October 2013 21:36:45
Lease Expires . . . . . . . . . . : 03 October 2013 21:36:45
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DHCPv6 IAID . . . . . . . . . . . : 318774674
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-19-C4-B6-AF-00-1D-92-84-E9-C7

DNS Servers . . . . . . . . . . . : 192.168.1.1
NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter isatap.default:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . : default
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 9:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes