Good news! Sony Service in Newmarket were awesome, and they fixed my laptop at no charge without any issues. Took it there, said what I thought it was, and a week later got a phone call saying it's done. They also refunded my $75 booking fee, and now I have an additional year worth of warranty for the broken part... the whole motherboard had to be changed I think. So yeah, if anyone has issues with GeForce 8400M GS, take it back where you bought it, and they *should* fix it.
Only fucking shit thing is, my Win7 RC expired in the meantime, and now I have to use Vista
