Needing info for new rig I want to build

Yo!

I don't do a lot of heavy-duty FPS gaming, but I do like the Flight Sims (FS X, FS Pro 2002, Combat FS 3, etc.).

I know that certain games tax a certain component more than the others (like The Sims taxes the CPU more than the video card), so my question is: Does anyone here know which components the FS's tax?

My wife's system is pretty high-end, yet it still seems that it could be better (be advised that I like to play these games with details on high). Her system is as follows:

ASUS A8N-SLi Premium, X2 4800+, 2 GBs Corsair RAM, nVidia 7800 GTX 512, Plextor 716SA DVD x2, WD 400GB HDD SATA 16MB cache, XP SP2b, X-Fi sound card.

Also want to know whether an AMD or Intel solution makes any real difference? Well, I guess it would if FS is a CPU-intensive game, eh?

Thanks for the info.

I should have written that I won't be using her system, but upgrading one that's like 5 years old. That system is a Socket A 1.2 GHz Thunderbird, 512 MB PC2100 RAM, an ATA 100 HDD, and an ATI AIW RADEON 8500DV video card with like 64 MB RAM (AGP 4x).

Yeah, even that system plays the game using low details, but it's really funny to see the planes from an exterior view: they look like the X-Wings from Star Wars!

Anyhow, I like AMD better than Intel, but I am more impressed with the performance of the Core 2 Duo CPU's from the Evil Empire than anything from AMD (sadly).

I might even consider going SLI with the XFX GeForce 7900 GS 480M XT. They seem to perform really good and are inexpensive.