Are you doing some kind of scaling? It looks much better when I scale to 110% (Chrome and IE), but at the default 100% I get the artifacts. Tried a few different zoom settings, some are ok, some are not.
On the HN site I can zoom to any size and the font renders correctly .
right now 48px: http://i.imgur.com/6osWiqq.png
fine at 50px (additional 1.05em) http://i.imgur.com/lafmcpQ.png
super easy way to get windows vms installed on virtual box. Installs as many versions of IE as you want/need, preconfigured on clean vms. The vms are provided by microsoft: http://www.modern.ie/en-us/virtualization-tools
http://stackoverflow.com/questions/10953037/google-webfonts-...
Regarding a windows machine, you can get a free micro windows instance on Amazon AWS.
https://dl.dropboxusercontent.com/u/1325900/Capture1.PNG
Windows 8 x64, Chrome 26.0.1410.64 m.