use the asio full duplex driver,

go into your audio options -> driver set up (somtimes called "advanced"
make sure that only your analog inpouts and out puts are ticked if you're not using spdif

when mixing turn off all inputs and set the buffer to 2048.

if you record try to record as dry as possible and add fx afterwards (and try to direct monitor)

if you have hyperthreading or a dual set-up then make sure the box is ticked in the asio set up as full duplex can make good use of this.

make sure you're plugging into a usb 2 port.

and finally.. buy some good ram - 2/3 gigs if you can..