AMD 64 (939) 3200 or 3500 cpu
Probably go for the 3200 for now. You can always upgrade to something alot faster later on. I have a 3200 and find it more than adequate, overclocks pretty well too.
MSI K8N Neo2 Platinum
You don't have to get two cards now, one of the selling points for SLI is it allows you to purchase another card next year which will keep you up with the latest games. This new card will also be quite cheap as it will be essentially a year old.
Also do you want PCI-E compatability?
I have head alot of good things about this board though.
Mushkin Dual Pack 184-Pin 1GB(512MBx2) DDR PC-3200
Cas Latency: 2.5-3-3
This ram will be fine, you're unlikely to notice much difference between 2-2-2 and 2.5-3-3 in real world terms, unless you are really bothered about benchmarking. Have yo read the compatability articles about ram in socket 939 systems though?
Harddrive- If you want a raptor why not get a 74gb one? They are slightly faster and quiter than the older 36gb, the difference is not just the size. I have heard reviews which show the raptor isnt that much faster than new hitachi drives, is it really worth the cost?
Formatting the drive.... for 80gb i usually do 10-20 gb partition for the OS 30-40 Games etc and the rest for downloads and general stuff. Obviously with a 200gb drive these values can be expanded, 20gb is more than enough for xp though 15gb is sufficient.
Video Card- Can't really comment here although if you do go down the SLI route Nvidia will be the better bet. gts are meant to overclock like beasts though!
Sound Card- Do you take your music seriously? If so ignor onboard sound, i find it terrible, it crackles and is nowhere near the quality of my 4 yr old soundblaster live! If you have any audigy this will be fine. A new audigy 2 can always be bought at a later date if you want EAX effects.
Case/PS- Again can't rele comment but SATA drives are the same size as IDE so they will fit and 3.5" drive bay.
Yes you could wait even longer until dual core A64s come out but that can be said with any hardware, it's always changing and you will never be able to keep up with it. My advice splash out now, you'll never be satisfied fully, but you can be for just a while! Hope that helps