I have a similar set up to you and upgraded with a bit of help from here. This is what I did. No doubt someone will correct me if I get it muddled. You need SP2 for USB 2.0 to be supported. USB2 can also conflict with USB1 so disconnect you old USB where possible. Go into Control panel, System, Hardware, Device Manager and delete anything to do with the old USB. Turn off and fit your USB2. Start up and Windows should detect your new USB 2. I only bought a cheap card from dabs.com costing about £6 plus postage as my system is over 4 years old and pretty creaky now but it does the job fine. Hope this helps.