This maybe to personnal taste but i'd recommend editing the template to a fixed width of maybe 750px.

On higher resolutions the 100% margins make your posts look a little skimpy. Considering the blog type layout i'd always go for a fixed margin.. it'll avoid you having a one line post spread across 1600 pixels. Least you'll know that how you see your posts will be the same for everyone else.

Ciarán