I had same problem several weeks ago when I upgraded my main mac (iMac) to OS Lion. I had been using Bonjour printing for both my HP windows 7 pc and vitrual windows 7 (macbook Pro OS Snow Leopard).
Both pcs started to print micro size and centred in page.
I have installed printer drivers in windows using driver for printer, and set as default.
It seems that to connect to Mac attached printer I needed to access the Mac UNIX printer system.
I installed using the network option, and somehow windows 7 found driver.
EPSON_Stylus_Photo_RX530 on http://***.local:631
*** is my mac name.
This may help