Logitech QuickCam Messenger

I've been following these instructions:
http://www.tomshardware.com/forum/ [...] enger-help

to try and get my QuickCam messenger to work here on my Vista but at this step:

7) When the next Box appears choose Let me pick from a list of device drivers on my
computer and "BINGO" you will see QuickCam IM in the list.

I find QuickCam IM in the list alright and click to install it and it begins installing but the error message comes up saying
"Windows found driver software for your device but encountered an error while attempting to install it."
and tells me that it cannot find the specified file.

Can anyone help? I've been trying to get my webcam to work for hours on end with no avail!