I have an issue with my Acer620U flatbed scanner.?

I just can't get it to work with my XP. When i install the Win98 version drivers from the CD it tell me they are not digitally signed. Searching on the net, I found an updated version of the Mirascan which I downloaded, When i try to start it, it tells me it cannot detect the hardware (which I have connected). The PC then claims it cannot find any drivers for the device. Even if they load, it stops and asks for the XP CD, then asks for TWAIN.dll drivers which I then load from the Hard drive. At the end of it all, it doesn't finish the installation, claiming, an error occurred. The pc also identifies the scanner as Flatbed scanner_13, but is unable to use the mirascan to make it functional. WHAT IS GOING ON? Do I need another driver?