Built new PC, Genuine Windows 7 fails to activate

I built a new PC about a month ago, and have installed Windows 7 Home Premium 64bit on it. I know it's genuine but it will not activate with my current key.

I'm pretty sure I know why. Because I had the same OS on my old PC with the same activation key which obviously activated fine. Now it won't activate because it's detecting multiple PCs attempting to activate with the same key. Obviously this is my fault for not "deactivating" the old PC, but it's unfortunately too late to go back.

I just wanted to know if there was any simple way to resolve this?

Thanks.

Here's my results:

Code:

Diagnostic Report (1.9.0027.0):
-----------------------------------------
Windows Validation Data-->

Validation Code: 50
Cached Online Validation Code: 0x0
Windows Product Key: *****-*****-9XXPR-38KVG-T4X7H
Windows Product Key Hash: DvVtODXfIgTTS52DVLWZX5boc5k=
Windows Product ID: 00359-113-2045944-85795
Windows Product ID Type: 5
Windows License Type: Retail
Windows OS version: 6.1.7601.2.00010300.1.0.003
ID: {979DDE0B-AE1F-4851-998D-C7358AECB25C}(1)
Is Admin: Yes
TestCab: 0x0
LegitcheckControl ActiveX: N/A, hr = 0x80070002
Signed By: N/A, hr = 0x80070002
Product Name: Windows 7 Home Premium
Architecture: 0x00000009
Build lab: 7601.win7sp1_gdr.120503-2030
TTS Error: 
Validation Diagnostic: 
Resolution Status: N/A

Vista WgaER Data-->
ThreatID(s): N/A, hr = 0x80070002
Version: N/A, hr = 0x80070002

Windows XP Notifications Data-->
Cached Result: N/A, hr = 0x80070002
File Exists: No
Version: N/A, hr = 0x80070002
WgaTray.exe Signed By: N/A, hr = 0x80070002
WgaLogon.dll Signed By: N/A, hr = 0x80070002

OGA Notifications Data-->
Cached Result: N/A, hr = 0x80070002
Version: N/A, hr = 0x80070002
OGAExec.exe Signed By: N/A, hr = 0x80070002
OGAAddin.dll Signed By: N/A, hr = 0x80070002

OGA Data-->
Office Status: 109 N/A
OGA Version: N/A, 0x80070002
Signed By: N/A, hr = 0x80070002
Office Diagnostics: 025D1FF3-364-80041010_025D1FF3-229-80041010_025D1FF3-230-1_025D1FF3-517-80040154_025D1FF3-237-80040154_025D1FF3-238-2_025D1FF3-244-80070002_025D1FF3-258-3

Browser Data-->
Proxy settings: N/A
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Win32)
Default Browser: C:\Program Files (x86)\Mozilla Firefox\firefox.exe
Download signed ActiveX controls: Prompt
Download unsigned ActiveX controls: Disabled
Run ActiveX controls and plug-ins: Allowed
Initialize and script ActiveX controls not marked as safe: Disabled
Allow scripting of Internet Explorer Webbrowser control: Disabled
Active scripting: Allowed
Script ActiveX controls marked as safe for scripting: Allowed

File Scan Data-->

Other data-->
Office Details: <GenuineResults><MachineData><UGUID>{979DDE0B-AE1F-4851-998D-C7358AECB25C}</UGUID><Version>1.9.0027.0</Version><OS>6.1.7601.2.00010300.1.0.003</OS><Architecture>x64</Architecture><PKey>*****-*****-*****-*****-T4X7H</PKey><PID>00359-113-2045944-85795</PID><PIDType>5</PIDType><SID>S-1-5-21-1524002986-3341039342-2201249097</SID><SYSTEM><Manufacturer>System manufacturer</Manufacturer><Model>System Product Name</Model></SYSTEM><BIOS><Manufacturer>American Megatrends Inc.</Manufacturer><Version>1606</Version><SMBIOSVersion major="2" minor="7"/><Date>20120816000000.000000+000</Date></BIOS><HWID>95C93207018400FE</HWID><UserLCID>0C09</UserLCID><SystemLCID>0409</SystemLCID><TimeZone>AUS Eastern Standard Time(GMT+10:00)</TimeZone><iJoin>0</iJoin><SBID><stat>3</stat><msppid></msppid><name></name><model></model></SBID><OEM/><GANotification/></MachineData><Software><Office><Result>109</Result><Products/><Applications/></Office></Software></GenuineResults>  

Spsys.log Content: 0x80070002

Licensing Data-->
Software licensing service version: 6.1.7601.17514

Name: Windows(R) 7, HomePremium edition
Description: Windows Operating System - Windows(R) 7, RETAIL channel
Activation ID: 2e7d060d-4714-40f2-9896-1e4f15b612ad
Application ID: 55c92734-d682-4d71-983e-d6ec3f16059f
Extended PID: 00359-00170-113-204594-00-3081-7600.0000-2712012
Installation ID: 009735637684470245046642529901815840912834008606601573
Processor Certificate URL: http://go.microsoft.com/fwlink/?LinkID=88338
Machine Certificate URL: http://go.microsoft.com/fwlink/?LinkID=88339
Use License URL: http://go.microsoft.com/fwlink/?LinkID=88341
Product Key Certificate URL: http://go.microsoft.com/fwlink/?LinkID=88340
Partial Product Key: T4X7H
License Status: Notification
Notification Reason: 0xC004F009 (grace time expired).
Remaining Windows rearm count: 4
Trusted time: 31/10/2012 7:43:58 PM

Windows Activation Technologies-->
HrOffline: 0x00000000
HrOnline: 0xC004C532
HealthStatus: 0x0000000000000000
Event Time Stamp: 10:31:2012 17:03
ActiveX: Registered, Version: 7.1.7600.16395
Admin Service: Registered, Version: 7.1.7600.16395
HealthStatus Bitmask Output:


HWID Data-->
HWID Hash Current: PAAAAAIABAABAAIAAQADAAAAAgABAAEAHKIw1040OXYSwnTEZMcKUxhYPhx6y96IgkwyqFw/OpZelZZj

OEM Activation 1.0 Data-->
N/A

OEM Activation 2.0 Data-->
BIOS valid for OA 2.0: yes, but no SLIC table
Windows marker version: N/A
OEMID and OEMTableID Consistent: N/A
BIOS Information: 
  ACPI Table Name    OEMID Value    OEMTableID Value
  APIC            ALASKA        A M I
  FACP            ALASKA        A M I
  HPET            ALASKA        A M I
  MCFG            ALASKA        A M I
  FPDT            ALASKA        A M I
  SSDT            SataRe        SataTabl
  SSDT            SataRe        SataTabl
  SSDT            SataRe        SataTabl

Edited

"The product key you typed cannot be used to activate Windows on this computer"

Funnily enough, it was a friend of mine who entered it after we built the machine, and I left the case at his place. He's a computer tech who enters keys all the time so I would give him the benefit of the doubt, but I'll have to see about getting the case back and re-entering the key.