I was thinking of doing a system upgrade for XIV, since I only have a dual-core processor. However, I was seeing some reports in the beta forums that the game doesn't use more than two cores anyway. I managed to get my hands on a friend's new quad core system, an AthlonII X4-640, so I was able to verify the behavior of the client on windows XP SP3 (32bit).
In order to make sure my graphics card (GTS250) would not be a bottleneck, I changed all graphics settings to their minimum. During testing the card's load never got above 40% according to GPU-Z.
Using those lowest settings with my dual core system (e8400 @ 4.2GHz), the framerate would drop to 32-36 with around 20 characters onscreen. CPU usage was at 95-100% during this time -- both cores fully in use. Using Process Explorer I saw that 2 threads were using the majority of the CPU time.
I migrated the windows install to the new Athlon system (new drivers, etc) and placed the same video card inside it. In the same conditions as with my e8400, I was only getting 17-24 FPS! Processor usage total was only 50 to 55%, and I saw that with Process Explorer the same two threads were using the majority of the CPU time. Once I installed the support pack for AMD's Cool'N'Quiet (adjusts clock speed depending on CPU load), the framerate was even lower -- 14 to 16 fps.
Looks like the client currently really doesn't use more than 2 cores, so I'll skip the upgrade for now! Still need a $400 video card though, the GTS250 is just too weak.
XI Wiki


Also, for those unfamiliar with my previous post, this is not something she will be gaming on for the rest of time, it's a mobile option, and a patch up until PS3 version comes out.
