I emailed Acer about the problem with their chipset driver
link, and they hastily replied with a link to the same driver that I told them was the wrong one. It wasn't a confusing letter, just straight to the point. I'm not surprised at their incompetence, just amazed that here it is three months after the official release of Windows 7 and still no driver for this. However, I did notice that the Aspire 4520 isn't in the list of Windows 7 compatible machines. I went ahead and installed the Vista Ultimate x64 chipset driver in Vista Service Pack 2 compatibility mode. I haven't bluescreened yet, but I am still afraid to run Windows updates. My computer is working fine and I have too much work to do to have anymore setbacks with that.
Oh, the CIR driver is for the Infrared Transmitter on the front of the computer. I'm guessing yours has one. I've never used it, but some older cellphones had them to transfer files wirelessly before bluetooth. I'm sure it doesn't hurt to install that driver.
I'll post more on this if Acer sends me anything useful or if I figure something else out.