This archive contains a few versions of drivers supposedly made for the ZA-ACM-VC18U USB webcam, made by Zaapa. The drivers might work for other models as well. The electronics inside it are made by Empia. Like Ati or Nvidia make video card chipsets, and others (Sapphire, Gainward, MSI, HIS, ASUS, etc.) make the actual video card. I succesfully attempted to find drivers for this webcam, for Windows 2003. Silvercrest also made at least one webcam model with Empia electronics inside, with 1.3 megapixels.
In this archive you have the original archives from Silvercrest (DRIVER_50946) and an archive I found that was said contains the original drivers from Zaapa (webcam). The Empia drivers can be found at http://www.empiatech.com.tw under "Support" and are called "USB PC Camer