Graphics RAM: Looking to watch some high-def YouTube clips or enjoy the occasional Blu-ray video? Most people have no need to pay more to go from 1GB to 2GB of RAM on a midrange graphics card. The graphics board that ships with your PC will more than likely be enough--even the integrated graphics capabilities of AMD's Fusion chips and Intel's Sandy Bridge lineup will be more than a match for your media.

Gamers are the exception here, as a beefier card with 1GB of RAM will outpace a 256MB or 512MB counterpart. The 2GB realm is generally reserved for the $700-and-up, enthusiast-level cards--a different beast altogether.

Really high amounts of graphics RAM are useful primarily on very high-end graphics on very high-resolution screens. A faster graphics chip with less RAM will almost always produce better performance than a slower chip with more RAM. Related:

Quad-core processors: In the world of laptops, a dual-core processor is likely to be faster than a quad-core for most of the mainstream applications that the majority of users run; a dual-core CPU often operates at a much higher clock speed, and most general-purpose applications don't make good use of four CPU cores.

But if you do a lot of video-processing tasks, heavy scientific computation, or engineering work, four cores may be a great way to go. If you want to buy a future-proof desktop system, keep in mind that multithreaded applications are becoming the norm, and your PC will be able to hammer away at more tasks if it has a bit of extra computational headroom. Truth be told, unless you're looking at a particularly low-end desktop, it's difficult to find a desktop PC that isn't already sporting a quad-core CPU. Related: