This guy has some good intructions.
http://rdmsnippets.com/2013/05/29/setting-up-asicminer-block-erupters-on-windows-7/I got mine up and running on a Windows 7 and a Windows XP machine.
Download the correct drivers from
http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspxI had problems letting Windows search for the driver on the XP machine. It found the wrong one. Under Devices in the Ports section it should say Silicon Labs CP210x USB to UART Bridge (COM3)
Yours may have a different COM number. Mine was 3. It is important for the command line later on.
I was initially unsuccessful with CGminer 3.2.0 but it may have been my problem.
I backed down to cgminer 3.1.1. Created a short cut to cgminer-nogpu.exe.
The I edited the properties of the short cut so the Target looks like this on the Windows 7 machine
C:\cgminer\cgminer-3.1.1-windows\cgminer-nogpu.exe -o stratum.btcguild.com:3333 -u yourusername_2 -p 123 --icarus-options 115200:1:1 --icarus-timing 3.0=100 -S //./COM3
And this on the Windows XP machine
"C:\cgminer\cgminer-3.1.1-windows\cgminer-nogpu.exe" -o stratum.btcguild.com:3333 -u yourusername_3 -p 123 --icarus-options 115200:1:1 --icarus-timing 3.0=100 -S //./COM3
Note the parenthesis on the XP command. I do not know if it is critcal but it defaults that way.
The name after -u is really the worker name for btcguild. Which in btcguild is yourusername_suffix. So I have two workers called yourusername_2 and yourusername_3. Some of the examples have periods instead of underscores and I don't think that works with btcguild. I have played with any other options. Both units are hashing around 334M. And btcguild does not care about passwords for the stratum servers so use "123"