Dude, I'd be very wary of a possible spouse that would actually snoop around on my computer, and if you don't at least address that issue, you might be looking at more serious issues down the road.
I didn't think your MySpace comment was that big of a deal, but in that she did, you might want to suggest what is and isn't acceptable in your dealings with other people of the opposite sex.
You might also want to agree to what boundries you both need as to privacy issues in the future. If you both are comfortable with being totally open books with each other, great, but if not, it's not fair that one party feels the right to snoop on page after page of private computer correspondence.
Good luck to the both of you.