Is it possible to force MrPoster to install against a newer version of the .NET runtime (v2.0)? Crossover Office (at least the 6.2 beta) can install .NET 2.0, but it appears your app still *insists* on using v1.1, which will not install under Wine/Crossover Office.
At this point, offline eBay posting is probably the last app I need to migrate my brother's system off of Windows. So depending on which one of the trio of MrPoster, TurboLister or Poster Toaster is the first one to work on Linux, that will decide which app he uses in the future.