Opera is fast because it loads elements in sequential order as a list of instructions, which discourages freezing or becoming unresponsive for fractions of a second which added up slows down the overall load time. Google is fast because it loads each tab, treating it like a new process. Firefox versions above 7 have been known to be faster than all of it's pre-versions because of just better coding and multi-threading. Google takes advantage of a unique version of multi-threading. And with IE which seems to be fast for me using IE9, i'm not so sure.
If a browser combined that of what Google does by loading each page into a new process, and having each element on the page loaded separately like Opera does, and functions were executed on numerous threads inside each process which would be available for every tab though. Then you'd have a real ultimate version of a web browser currently unknown to man.
There's positives to each browser out there. Having known background knowledge in programming for various languages I can understand somewhat of how each works though.
I don't understand what you mean by 2007 Windows though, there's no such thing. Unless you're talking about release dates, then you don't have Windows 7 and you're currently on the wrong forum.
Vista was released somewhere around 2007, Windows 7 was released around the year 2009 I believe?