I'll give you the honest answer:
it depends on what you want, and specifically what you can tolerate (or ignore). 🙂
I say that because sooner or later new games or system usage will require certain settings toned down to compensate and still provide a smooth experience. How much you can tolerate, and how fast that happens, I don't know. 😉
I am in a similar position (actually nearing the "submit order" button on newegg right now for a new build, still tweaking and looking around locally for some things).
However, you have more time on your hands, so there's that. 🙂 My CPU (C2D 6420 oc'd to 3.4ghz) is a serious bottleneck in quite a few games. Quite a few games are starting to really beg for either an incredibly awesome dual-core chip, or most often a fairly recent quad-core CPU.
The Battlefield games of late have basically demanded a quad-core if you wanted to enjoy the game with everything at least at decent quality levels.
I imagine the better quad-cores of the Core2 generation will keep up for quite a while, so long as the rest of the system isn't a major bottleneck.
It's to the point with the C2Ds that better GPUs aren't going to cut it, since so many new games demand quite a lot of computation for the core parts of the total engine package. In Battlefield series, it works beautifully with quad-cores, because one core is doing audio, and one core is doing physics, while a third works on graphical details like lighting/shadows (iirc). Not sure if all four cores are specifically used by the Frostbyte engine games, but the OS and system generally stress a some or most of a core...
