Honestly, I would say to take the money you would spend on the better processor and put that into getting a top-of-the-line video card, because when It comes to playing games, the CPU takes a backseat to the video card in terms of importance and the actual good it can do. But if your looking to be playing STO on the maxed out graphics while running a word processor, a web browser with 15 tabs open, watching a movie and maybe rendering 3D models all at the same time, yeah you might need a processor with like 8 or 16 cores. As for RAM, 6 gigs should be enough to run whatever version of Windows you have on the prettiest mode and play STO on maxed out graphics, but you probably wouldn't be able to do a whole lot else, maybe run a web browser in the background without any performance decrease, but I wouldn't push it much past that without upgrading RAM and having a decent CPU. Basically what I'm trying to get across is that if you have a dual-core 2.0GHZ CPU or better and at least 4GB of RAM (<-- not very much these days in terms of what it could be and price), the only component that will really matter is your video card, and any video card 1GB or above will do ya fine for the next three to four years at least.
EDIT: Also, hyperthreading will really only help you if you do a lot of multitasking with things that actually take up some horsepower. From what I understand, hyperthreading basically just helps the computer allocate CPU usage more efficiently when your trying to do more than one or two things at a time, so if your just typing up text files/surfin' the web or playing games then you don't really need it. However, if your surfin' the web, typing up a text document, playing a game, watching a movie, running some kind of packet-capture software on your network AND trying to do something else, yeah, you will need hyperthreading.
EDIT#2: If your somewhere between the levels of multitasking listed in the last two sentences of EDIT, then hyperthreading can't hurt, but it's probably not necessary per se.
