I upgraded both my motherboard and the os to windows 7(32bit) and now im lagging very badly. Before i had vista and Mass Effect ran very smoothly. And all my drivers are up to date.
I'm having a similar issue as well. Upgraded from Vista 64-bit to Windows 7 64-bit (using the in-place upgrade), and now I get big framerate drops every minute or couple of minutes. Mass Effect ran great before. On this setup: