I suggest ignoring the above answer. I've just done a W7 install on this mobo and everything seems fine. Not exactly a screamer but not particularly slow either. I can't use aero because of my graphics limitations but am not bothered.
But there is a glitch to overcome - certainly if, like me, you are working through the SATARAID interface. I don't actually use the raid facility but my BIOS invokes the option anyway. In that case the W7 install will not see any hard drives and will ask for drivers.
The zip file download URL is below:
http://www.siliconimage.com/docs/3112R_x86_10651_Logo_win7.zip
or you can find it by going to http://www.siliconimage.com/support/
selecting from the dropdown menu::
Sil3112-PCI to 2 Port SATA150
and choosing the 32-bit SATARAID driver dated 2/1/2010
Unzip the contents, stick them on a USB stick and browse to find it from the stick when the install asks you to. I was up and running in 20 mins.
No problems so far. It happily goes away and sucks up various drivers my equipment needs. V happy!