asic block erupter and bfgminer help needed please.

[spikey]

I can't get my miner working despite taking 2 days and reading every guide.
My system is Windows 7 64 bit. Normal 330 mhash usb asic miner.
I plugged in the miner, downloaded the Silicon Labs USB to UART driver as instructed.
This shows up OK in "devices and printers" but does not show a com port so I can't enter it into bfgminer.
Also when I unplug and replug the miner into my computer it doesn't make that usual usb noise anymore.
Can some kind soul help me out?