This is an answer 2 months later than you needed it, but I just got me a second hand Acer DC300. Having also had a hard time with it, here's my experience for the benefit of posterity:
Installation:
The instructions are pretty explicit, and apply to most imaging devices (scanners/cameras) that have a setup.exe mode of installation
0. If you have already done an unsuccessful attempt to install the drivers, make sure you run the uninstall program (unchdrv.exe located in Acer folder)
1. WITHOUT the camera plugged in, install the drivers.
2. Then it is MANDATORY to reboot immediately, without doing anything else. So before starting the installation, make sure that no programs are running, so you can reboot immediately.
The tricky part is that after the reboot, you have to plug in the camera 2 TIMES !!! This is because the camera has two distinct modes of operation: videocamera and picture camera.
Before anything else, exit from the resident DC300 monitoring program that resides in the taskbar, because it may (and will) interfere with the "new harware wizard".
3. Then power the DC300 ON. This puts it into PICTURE MODE. Plug the USB into the DC300. The new hardware wizard appears. Click OK in the "unsigned driver" warning and you'll have the PICTURE PART of DC300 ready.
4. Plug the DC300 out and switch it OFF. The camera now will operate in VIDEO MODE, when you reinsert the USB plug.
5. Reinsert the USB plug. The new harware wizard appears. Click OK in the "unsigned driver" warning and you have the VIDEO part of DC300 ready.
Now you can run the camera's utilities and you'll see that everything works OK. It's my first webcam/camera device, but I bet most cheapo ones need the same care for installing the drivers.
One final thing: don't expect the DC300 to appear in your Imaging devices (scanners and cameras in Control Panel) - the DC300 is neither. However it will appear as an vfw video capture device in all your video apps, including Netmeeting (NM). (By the way, NM is standard in windows XP (i think from SP1a and SP2), although it does not appear anywhere. To run it, do Start/Run/conf.exe - this will start the NM setup wizard.)
If you manage it, please send me a mail or post a reply regarding how many frames per second you achieve with DC300 - here I can't get more than 2.2 fps. I guess this bitter truth, although in the specs 30 fps are stated (alas, it seems this refers to the videorecording mode and not the webcam mode....)
I hope the above helped you. Good luck!
