Any question answered...

When I say soundcard, I mean 'audio interface' so a USB or firewire audio interface from the likes of m-audio, echo, etc etc.
Native windows audio is notoriously bad for latency without custom drivers written for specific audio hardware.

what's the A&H thing? allen&heath dj mixer? does this have an audio interface or just used for mixing?
you could try ASIO4ALL drivers too, they might help, but it's going to a kludge solution.
I'd suggest getting the NI traktor USB audio interface thingy.

A&H XONE DX

http://www.allen-heath.com/uk/Products/Pages/ProductDetails.aspx?CatId=XoneSeries&ProductId=XoneDX

It has its own soundcard. I suggested ASIO4ALL already (I use them with Ableton and um.. name escapes me) but they didn't work either apparently.