I am developing web site.Which scripting language should I prefer VBScript or Javascript?

Javascript, IMO. Javascript is more readily understandable to most browsers. While VBScript is making some kind of attempt at becoming popular, it may very well only be supported by "popular" browsers. I'm not 100% sure, but I don't think the little guys, such as opera, support VBScript, while they are much more likely to support Javascript. It just seems like the better plan.

Java/JavaScript with no doubt

"Java" isn't synonymous with "JavaScript". Two entirely different languages and methodologies.

VBScript is Microsoft; JavaScript is open-source. Go with JavaScript.