If you want a 2.6 GHz processor, then Intel is the ONLY way to go unless you want to buy an Athlon XP and overclock it. I'd get a 2.4 GHz Pentium 4 C core. They run at 800 Mhz FSB and are equipped with Hyper-Threading technology.
I'd get 512 MB of PC3200 RAM. Corsair, definitely. If ya wanna get more ram but spend the same money, then get PC2700 and just up the MBs.
The GeForce FX 5800 is the only FX that is loud as hell. The rest are fine. I have a GeForce FX 5900 Ultra and it's just as loud as my old GeForce 4 TI4200.
If you go Intel and get a Pentium 4, then nForce 2's are out of the question. And yes, nForce 2's *are* that great.
If you want a Radeon 9700 Pro, then get a Sapphire or ATI. Those are the two best, and nearly the only manufacturers that I would trust with ATI GPU's.
If you want to go AMD and NVIDIA, then get a nice Abit NF7-S motherboard with a Athlon XP Barton 2500+ processor. The NF7-S comes equipped with the nForce 2 chipset which is amazing. I'd get a GeForce FX 5900 Ultra, on top of that. May as well, since you're getting an NVIDIA chipset on your motherboard.
If you want to go Intel and ATI, then get a Pentium 4 2.4 GHz C Core processor and some kick ass Asus motherboard (I'm not into Intel or ATI, so I my experience is very limited with both). As for video, a Sapphire Radeon 9700 pro or Sapphire Radeon 9800 Pro should do the trick.
Go Intel if you want to spend way more money but want the best performance right now. If you want to save money and get a HELL of a computer for damn cheap, then go AMD. Good luck!
-Lasereth