I read a review in PCA or some other magazine that hyper-threading technology actually slowed things down. The reason being, software needs to be designed to use it. At the moment, theres no software on the market that can use hyper-threading to the fullest.
I read that hyper-threading allows the PC to work like two. The technology makes the processor do twice as much calculations per second.
If this is gonna a PC that you are hoping to keep for a long time, then I would go for hyper-threading.