DDR2 I don't think is that much faster compared with DDR components at really fast RAM speeds anyway.
yeah that soundcard should be good.
You do know don't you though if your not bothered that yuor motherboard you chose up there ^ comes with onboard multi-channel sound anyway on the chip?
Though its true getting a sound card to fit in a PCI slot will take the load off the processor for gaming and such (since sound cards on motherboards use precious CPU time)
As for the motherboard, whats wrong with PC3200 RAM?
, most boards support that at max anyway
As for the processor. I seriously wouldn't spend that much on getting the 3800+ though its true it would last you a long time and since it supports 64Bit, as soon as the new OS's come out and more programs use it, you'll get a boost straight away, so yeah.
Though it would be more worthwhile going with a 3500+ since it'd still be a great system, and won't cost a bundle more which you can just spend on someting more worth while like a better graphics card. Don't you think?
Though its up to you, and that graphics card is rather good anyway.
Choosing PCI-E though is a great choice for a new system though, since you can always update to a better card later on