(Driver issue) Sony VAIO VGN-AR71M + NVIDIA geForce 8400M GT + XP64bit downgrade

[opusensemble]

I'm the proud owner of a Sony VAIO VGN-AR71M, but a frustrated user of Windows Vista (its default OS and apparently the only OS supported by Sony on their site for this model). So I've decided to downgrade it to XP64bit. Everything went smooth, except for the part of the NVIDIA driver. I got stuck on it.

Does anyone know where to find XP64bit drivers for NVIDIA geForce 8400M GT ? Or a way of tweaking existing drivers or .INFs so that XP64 accepts them?

(Which driver installer and modified .INFs should I use?)

Your help is valuable and most welcome.

Kind Regards,

[opusensemble]

Meanwhile I've tried 190.15_winxp64 + the modded .INF from this site, and the installation process does not show me any error.

However, I get this message in the end, and no driver is installed.

http://img12.imageshack.us/img12/9256/diags05.jpg

Any hints?

[opusensemble]

Meanwhile, tried to do it manually, but still no luck

Although the video card string is shown:

http://img20.imageshack.us/img20/6250/diags06.jpg

I get the message that XP is not supported

http://img31.imageshack.us/img31/4546/diags07.jpg

(which is odd as I've used the modded inf for the XP 64bit driver)

Any clues?