Cellus

No the dual-core architecture should not be interfering with dealing any "incompatibilities" if the motherboard supports it. Dual-core processors simply have two execution cores - pretty much everything else is the same (with a couple exceptions). Windows XP can dynamically handle the load between the two cores (albeit not perfectly) - to get the best results the program needs be aware and use multi-threading, but as far as I know Battlefield 2 has yet to support it.

There are probably other factors not being accounted here as well - drive fragmentation, patches, background processes, and so forth. I should note that BF2 will take longer on the first run and any other runs where configuration changes are made as it optimizes the shaders. Those factors need to be considered in performance as well, not just the hardware. I have seen older PCs run laps around bleeding-edge PCs because they were not updated and patched, had drive fragmentation, were running a billion background processes, and so forth. Also, the GS series of cards are not nearly as good as their GT cousins by a significant margin.