if it was my system....
- i'd change the CPU to a San Diego 4000+
- wouldn't bother with a 10k drive, they're way overpriced for the extra performance they give. -- with HD space, just get what you are sure you will need, don't bother buying a 200Gb HD if you're not going to use it all. have you considered getting SATA2? its barely more expensive, and its got 2x the bandwidth.
- go 8ms 19" instead of 4ms, i doubt anyone can tell the difference and you'll be saving money that way.
what speakers are you going to get or do you have atm? because onboard sound for nVidia chipsets has and is and always will be awesome, so unless you've got really nice speakers, you won't hear the difference anyway.
- no need for a 600W PSU really, at least not one that costs $200. I'd recommend an Antec Truepower 2.0 550W
- Like the other's said, DDR2 won't even fit into an AMD motherboard at the moment, so don't bother looking into it. make sure the ram you buy has good latencies, AMD's really like tight latencies.
- i'd want to get a Single 7800GTX now, and then later when you want to upgrade something, just grab another one, and you'll get a nice performance increase without having to change both at the same time.
thats all i'd change i think, it looks like an awesome system