It looks like you're new here. If you want to get involved, click one of these buttons!
On the processor side, Intel is set to launch Haswell, which will greatly reduce idle power consumption as compared to Ivy Bridge. This is a huge deal in tablets, and very nice in laptops. But it's irrelevant to desktops. Haswell should bring a variety of small performance improvements, but not really a big deal in desktops. And without a new process node, it won't likely bring much in the way of improved energy efficiency at load, either.
Intel is also set to launch Ivy Bridge-E. Have you seen the prices of Sandy Bridge-E? Enough said.
And then there is Silvermont Atom, which might be a nifty chip for tablets or netbooks. But not desktops, as Atom is low end.
Meanwhile, AMD will launch Kaveri, the successor to Trinity. Kaveri also brings a die shrink from 32 nm to 28 nm, and AMD is promising considerable performance improvements. Kaveri might well be a great laptop chip. But in desktops? As it won't go over four cores, it has no real hope of catching a Core i5-2500K in single-threaded performance, nor an FX-6300 in highly-threaded performance. And those aren't exactly today's high end, either.
Moving down the chain, AMD will launch Kabini, based on Jaguar cores, and basically the successor to Brazos. But like Silvermont Atom, Kabini is low end. It might be a nifty chip for netbooks, and the Temash variant probably will be a nifty chip for tablets. But Kabini isn't going to matter for desktops unless your overriding goal is an ultra-small form factor, in which case, Kabini will probably get you something functional in a case smaller than a lot of books.
And then, at AMD's high end, there is the unannounced successor to Vishera. The reason it isn't announced is that it won't launch in 2013. Boring year, eh?
Then there are video cards. With no new process node to move to, neither AMD nor Nvidia will be able to improve performance per watt much. As they're already limited by power, this means neither will offer much in the way of performance increases. Both will launch new cards in 2013, but they'll be highly derivative of this year's cards.
But that's not to say that desktops are dead. 2014 brings Intel Rockwell, which is a more-than-a-full-node die shrink of Haswell. It will also bring AMD Excavator cores, and likely a real successor to Vishera. Hopefully AMD will be able to move to a 20 nm process node in 2014, rather than being stuck at 28 nm and two full process nodes behind Intel, though that hasn't been announced yet.
On the video card side, 20 nm process nodes should be ready in 2014. That lets both AMD and Nvidia do a full node die shrink, which gets you about 40% more performance in the same power envelope. Or maybe more if they decide to burn die size to save power, since transistors will be getting awfully small.
DDR4 memory will likely also be ready in 2014. That lets you scale up system memory bandwidth without needing to add memory channels or go with high-voltage variants of DDR3. That's great if you want to feed integrated graphics more effectively.
The upshot is that if you're looking to get a new desktop, then there's no need to wait for hardware. You might want to wait for Windows 8 to launch tomorrow, but there isn't a bunch of important hardware coming soon that is worth waiting for.
Unless you're interested in a tablet, that is. Google just launched Chromebooks with Cortex A15 cores, so those should be coming to tablets shortly. Intel Silvermont Atom and AMD Temash will vastly improve over current generation products for tablets, too.