I am a Vietnamese so my English is not good. I love reading English books, especially programming books. However, my reading speed is terrible, there are too many new words and I have to look up dictionary frequently.
How can I improve my vocabulary to read faster and faster?

all I know is keep reading, comes in time
try reading "complete reference" books on languages....everything you need you can look-up in them

Are there any softwares which help me improve my vocabulary?
@to asbo: Haha, I found that you love Herbert Schildt's Complete References (you say about it everywhere). I have known "C++: The complete reference" since I began learning C++ and I like it, too.

I'm sure there are many programs, but I would suggest that reading good English news (paper or on the net) would really help you much more. BBC News might be a great place to start (it's already on your Firefox, just click "Latest Headlines" from your bookmark bar). If you have a television, I believe CNN and BBC Word are broadcasted almost everywhere in the world. Watching good English news can be a very good way to learn English.

I'm also moving this to Chit Chat and Hangout, as News and Discussion is mainly for YC news.

I'm German and my English isn't so good.
I want to improve my English, too.

There are many programs but probably it's not going to help you any better than taking a vocabulary and learning new words. Or at least if you bought a book and start self-teaching.

I want to notice that howbad your English is - you still won't improve it in one or two days. As Umang said, read English articles, news... There are tons of tons news websites! Watch movies in English, with subtitles in your mother-language would be perfect, start playing team-work games (online). At least I've found that my whole English language is from that kind of stuff... I always liked talking on chats with my teammates or just friends... I mean talking on a voice-chat, not the usual type-in chat. Probably every online game has a bunch of people (at least) who talk on Ventrilo or any other such program.

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How to set up portable C++ IDE (Dev-C++)

Writing in C or C++ is like running a chain saw with all the safety guards removed," — Bob Gray.

My English is not very bad, I can read and understand English books but my reading speed is slow.
Thanks for all supports!

Ahh, it's a different story. Sorry that I didn't understand your problem at first. Try watching this speed reading tutorial. They've got more videos (not only those 5 I suggested to watch) on the channel (you'll see) as well so you can watch them as well.

The reason I suggested you those videos because I had the same problem. I don't really like reading books and still some people who didn't read books could read pretty fast so I was like "huh, how can he read so fast? I believe he doesn't read many books". That was because I thought the more you read - the faster you read. Actually it's not all about reading - watch videos. I've found them useful as now I can read as I used to and to read fast if needed, but still, when I read fast, I miss some small stuff - I'm still at school and so I have to read carefully in literature lessons and etc...

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How to set up portable C++ IDE (Dev-C++)

Writing in C or C++ is like running a chain saw with all the safety guards removed," — Bob Gray.

well...in most of the places there are spoken English classes at a nominal free...i would recommend u to go to one of them...cuz only they can correct ur pronunciation as they are hearing u....

Unfortunately, there aren't any such classes in my place.