ASUS Xonar DX or similar soundcard

On what account? You’d best do some research before buying stuff. Unless you favor higher SNR over proper hardware acceleration for gaming there is no reason to get the Xonar over the Auzentech or Creative cards. The whole Eax/DirectSound/OpenAl debacle is the most misunderstood and misinformed issue in history with people talking crap without knowing shit.

Of course it comes down to whether you care or not. You can always have the typical Indian mentality and get the cheapest possible shit without care for anything else.