By coincidence I was discussing Orwell with a friend last night. We decided that while 1984 was fine sociology and politics, the plot really didn't depend at all on the small amounts of technoogy he described. The surveillance could have been provided by spies as well as by TV screens and cameras. "SF" isn't a category we'd put Orwell into.
Um, science fiction doesn't have to be technology-focused, and most of the best stories aren't (with some exceptions where some exotic tech is a plot device). Sure, as many sci-fi stories occurs in the future there is an assumption that new technology have been marching on, but many interesting stories concern themselves with how humans react to the possibilities enabled by technology and new societal structures, rather than the technology itself. Nineteen Eigthy-four is specifically a future dystopia, but I'd certainly place it within the Sci-Fi genre.
On a side note, I've found that providing performance specifics about technology, specifically computers, are a sure sign of *bad* Sci-Fi. I read a novel written in 1992 set in 2007 where one particular computer had a CPU of 400 MHz and was equipped with "several hundred megabytes of memory". Bad Sci-Fi writers: restrict yourself to describing what amazing feats the wrist-computer is capable of, do not venture into providing explicit hardware specifications