I am writing my masters thesis on Open Source video games.  For the purpose of comparison, I am looking for detailed sales information for commercial PC games, preferably in a format comperable to the weekly charts for console game sales on this site.  While I can find monthly charts of PC games, these generally do not include information on the number of units sold, or the number of units sold per week or per month.  Any help would be much appreciated.

Sorry but there are no tracking firms that publish actual sales figures for PC titles.

The best thing you could do is email the publishers of specific titles and request shipment numbers but even that is a lot of leg work with probably very little results.

try wikipedia, i think they have a list of games that have sold 1m+ on pc alone.