Just to give you guys a quick tip:
The guys at Red Vs Blue (A Bungie/Microsoft sponsored Halo 3 Machinima group) got an early copy of the game (complimentary of Microsoft).
Their achievement hunter site has some good tips on achievements and so on if you are looking at them.
http://rvb.roosterteeth.com/games/halowars/However, be warned, they are comedians who make videos using the M Halo 3, so some of their other videos have violence and language (all in Halo 3/other video games). Halo Wars is a "T" game so I wouldn't recommend checking out their site unless you were fine with Halo 3 levels of violence (which admitedly isn't like Gears or GTA) and very strong language.
The achievement hunter videos, however, don't really have language. You can also find them on youtube, without using their site, which wouldn't be bad.
93% of statistics are lies.