I'm surprised at how many people are still using older versions of ACID. Acid pro 5 is only $200.00 and Acid Music Studio 6 is only $69.00. For $69 you get ASIO support, VST and DX support which is totally omitted in older versions of AMS. Time to upgrade.
I still use ACID 3.0 because it's paid for and I'm used to it. I really know it in and out and I have no pressing need to upgrade. If I have $200 to spend I'd rather spend it on something else