jerseygamer :
Not bad choises tbh. Great case. Great cpu. I would go with the Asus or Gigabyte MBs as I am very please with the quality and the OC above average OC ability unless you are an avid OCer then DFI but only if you are into the OC stuff heavy as they perform like pooo out of the box. For your gpu I would go for Asus. Just in the fan controls alone its worth it. You can set your fan to a % of speed based on 4 different temps. This allows your card to cool in steps rather then ramp up to 100% the second it gets hot. My 8800GT single slot for example stays under 44-45c at all times and never hits over 75% fan speed. The Asus cards come bone stock clocked. The utility is killer in that it allows you to monitor your card fully and keep stock clocks until your gpu needs more power then it will OC the card on the fly if you set it up that way or maintain the OC full time. I can not speak for Saphire as I have not installed one in a while but they are also very well known for high quality product. I can not testify as to the quality of there utilities though.
I can recomend against any EVGA or BFG product as they hardly test what they sell and are the industry leaders in RMAs and have the worst %%% of shipping OCed hardware with bad ram.
If you go vista go 64. Its worth it. You have the perfect ram# and you will reap all the benifits of a 64bit OS and future proof your system even more.
Have you given thought to a sound card? That system realy deserves a nice xfi to make it stellar.
Where's your argument about dx10.1? Oh, I see, you're talking about your gf8800GT so that would make you a hypocrite. Now I get it.
Is that your personal experience with EVGA or BFG? Aren't they supposed to have the best warranties? A lot of people prefer EVGA for their step-up program.
@OP:
ASUS makes some good video cards, but in my experience (that means I have actually owned them) they usually come at a premium. That doesn't mean I'm recommending against them, as they are quality parts, just shop around and compare prices.
Motherboard: Like Jersygamer said, ASUS or Gigabyte make great P35 boards, stick with them and you should be fine.
CPU: e8400 will be fine
memory: if you are going to overclock, I'd recommend either Corsair or Crucial high performance models. (I happen to favor Crucial)
HDD: Western Digital AAKS models or Seagate 7200.11
Monitor: Samsung, Dell, and Viewsonic are good places to start looking at 24" monitors, but there are tons of vendors/models out there, just post here so people can give you feedback on what you're thinking of getting.
Regarding sound cards: As I've recommended many times, evaluate your onboard sound from the motherboard first, then if you are unhappy with it you can invest in a sound card.
Looks like you're on your way to a solid machine.