Need advice on CPU and motherboard from the experts

P5Q -E... yes it's technically a CF board but really it's just a solid overclocker with a lot of good features at a good price.

Q9550 because the extra speed really will make a difference in games, but more games in the future will use multithreading... and your video encoding software will like it too.

I think a 4870 would be fine. Given your monitor you might get more time with an X2 however, before obsolescence.

A Corsair 650TX PSU would be a good match with those parts.

I havent purchased any components yet. I was thinking of the Antec 900 as it seems to be well liked. The P182 by antec also appeals to me as Im not much for the bright lights.

I was thinking about the corsair power supplies.. 650 versus 750. I just need to do a little more research to make sure I am not shorting myself on power if i need it. I would rather just get a 4870x2 than crossfire. Im also planning for Vista 64 and starting with 4gb ram.

I plan to do most of my spending through Newegg... i have had good experiences in the past and am more worried about reliability than absolute price savings.

Asus and Gigabyte seem to be pretty solid on Intel mobo's. Gigabyte might be just a bit better (very slim difference). Depending on what your budget is and what your looking for in a mobo (options). I've have a comparison of several p45 mobo's here. Any of these will be just fine for what you want. The budget can sometimes dictate what you can afford and thus what will work for you.
As far as the PSU's, you are selecting very good PSU's. I'd go with the Corsair tx 650w as a good starting point. If you want to leave room for more upgrades later than the Corsair tx 750w would be a good one to have. Newegg doesn't always have the best prices on PSU's, so consider that.
Corsair 650tx at Buy.com. $93 - $20 MIR = $73!!
Newegg's Corsair 650tx. $110 - $20 MIR = $90.

Corsair 750tx at Buy.com. $104 - $20 MIR = $84!!! Only $11 more than the 650tx!!
Newegg's Corsair $130 - $20 MIR = $110.