If you truly have a problem with this, you'd approach this with a smarter sense than to be thinking that all the problem is related to the CPU. The CPU as a whole functions perfectly fine for what it does. It has two cores intricately designed on a single CPU socket package. I cannot help but side with mark and duvie for this. You've constantly downplayed the X2 CPU as though it has some sort of design flaw when it clearly has none. Games have constantly been programmed with the notion that it'll run fine with a single CPU. And with good reasons too. Programming multithreaded applications isn't easy and to implement something that can handle it takes too much time and resources (and we all know that time = $$$). The current market sees only a single CPU design. And that design has been in place for a very long time.
Now, you may argue and say that this is games that this topic is supposed to cover. Games are applications too. It just wasn't coded to handle multiple CPUs or send multiple threads. Okay, some programs handle it well and some don't, even though it wasn't coded with multiple threads in mind. But remember that it's still coded with a single processor in mind. And by many people's testament, setting the program's affinity solves that problem. It forces a software to believe that they're dealing with just "one CPU." How does the driver fit into all of this? It's there to give Windows a better understanding on how to handle this dual-core CPU. Much like how basic VGA drivers can work with many video cards, using the manufacturer's drivers lets Windows have a better understanding on how to handle the video card. So some problems become solved while others are partially fixed yet requires just a little bit more tweaking.
People can take my claim of owning an X2 at face value or shove it aside as "just another claim." But let others judge you for how you post. Your tone and your explainations will help people better understand whether or not they are willing to believe you. If you had posted explicit details down to the very clock speed, model, cache, stepping, motherboard make & model, RAM makes, timings, speed, or whatever intricate details that can somewhat prove your claim, then maybe people will start believing. But so far, I have heard nothing absolute and nothing substantial as to what kind of system you have.
I'd like to help but I have difficulty in believing what you say when you cannot post in a formal manner. And call me whatever you want if you think I'm sounding like some "higher than thou" guy. I'm only stating how I feel about this problem that you seek to resolve. We've no information about your setup and we don't even know if you truly own those hardware.
Give a full spec, and maybe those who have the same hardware(s) may give you some pointers. Until then, it's unlikely anyone would take your claim at face value.