Please help (DirectX issue)

Ok so ive been using my comp for some time now with no problems but today i got the game Republic commando. I installed it and tried to play and it says something like "you need directx 9.0c to play" so i press install directx, it goes through the whole install thing in like 0.0001 secs and says complete but when i press play it just repeats "need directx 9.0c" .

I go and check in Dxdiag to see which version ive got and it says "directX : Not found" ??? Ive tried downloading from different places and getting both netinstall and the "non-internet" install versions but doesnt help.

Also in some updates it gets an error telling me to check error file and this is what the error file says: 

03/07/06 17:17:00] module: dxupdate(Sep 28 2005), file: dxupdate.cpp, line: 178, function: GetDXVersion

    Failed API:        RegQueryValueEx()
    Error:        (2) - Määritettyä tiedostoa ei löydy.



    Current DirectX may be a older version which does not have the version value in the registry.

--------------------
[03/07/06 17:17:00] module: dxupdate(Sep 28 2005), file: dxupdate.cpp, line: 3937, function: DirectXUpdateGetSetupInformation

    GetDXVersion() failed.

--------------------
[03/07/06 17:17:00] module: dsetup32(Sep 28 2005), file: dxupdate.cpp, line: 244, function: CSetup::InstallPlugIn

    DirectXUpdateInstallPlugIn() failed.

>>1
If DX failes that means you fail as well.

Somethings fucking directx good and its not obvious. I'd say update video drivers, run automatic updates, etc.
Copy and paste google your errors. If its a remotely common problem someone will have had it before

Stop using Internet Explorer.