Gotcha. As far as fitting your needs, you
do not need the newest, baddest-ass, and/or best components. Now, don't take that to mean that your system will run like crap - stuff from 8-12 months ago will still perform excellent for you based on your mentioned-usage.
Personally, for the system/jobs you're looking to do, I'd stick with a lower-end C2D and a MoBo around $70-ish. You could do with 1 Gig of RAM, but if you do a bit of comparing between TD and Newegg, you can almost always find a combo deal (2 x 1 Gig sticks) for either the same price or lower after Rebates. If you find such a deal, grab it, if not, don't worry about only 1 Gig. You don't need a monster PSU - 380-400 watts should be fine. Not at all familiar with that case, but if it appeals to you, go for it - that'll be what everyone sees
You mentioned being mildly interested in WoW; I'm assuming you have zero desire to game-otherwise? If that's true, then a low-end video card will be fine, however if you plan to do WoW sporaticaly at best, you may consider starting off without one and seeing how it runs using on-board graphics; you can always add one later if it lags a bit.
Will you be keeping your old monitor? If it's still in good condition, I'd stick with it. Newer LCD's will suck up a large part of that budget.