Many large commercial sites stick with the tried and tested default or left aligned page content. If you aren't going to go with a fluid layout which will resize at different resolutions then it makes sense to anchor your site in one form or another.
I rather like page content in the centre, but nothing works all the time for all content types.
In your case I'd say that a lot comes down to what you like. Why not let your own prefernce guide you.
At the end of the day there is no right or wrong method from a purely visual perspective. I like fluid layouts and mainly produce them for clients, but sometmies I get a design brief that insists on fixed width in which case I normally centre the page in the browser.
There are a ton of very successful sites out there that use left aligned, centre aligned and fluid layouts.
One of the pitfalls of presenting large bodies of text that I'm sure you've encountered is that it can really intimidate your visitors. Breaking up large bodies of text can become a real necessity otherwise your pages can seem barren, featureless and hard to cope with. It's always a fine line to tread.
Sorry if I'm not giving you a "do X, Y, Z because that's how it is". I don't think that the issue of whether your page content is left or centre in the browser is as important as how the content itself is presented. Good content in pleasant, friendly colours and fonts with crisp images and well thought out layouts and navigation looks good left or centre in a browser.