Why Windows 7 will be a massive success

Windows XP was massively popular, Vista is in the Shadows, but IMHO will provide a good stepping stone towards Windows 7, which will be more popular that Vista, which Windows 7 will build upon (and be 100% compatible with).

Windows XP has been a very popular OS, it managed to successfully build on the rock solid Windows 2000 and replace the lack-lustre Windows ME in one fell swoop. XP SP2 offered a significant improvements to further improve the reputation and popularity of Windows XP. Read Features_new_to_Windows_XP - Wikipedia, to find out more about about what was new in XP.

Windows XP managed a reign of approximately 5 years before Vista was finally released.

Vista has not met expectations on many levels, slipped release dates, number of features dropped, poor release reception, manufacturers complaints about lack of support to get drivers ready for launch, then compounded by other bad press Microsoft has had around and since Vista launch. Read Windows Vista - Wikipedia for more information about Vista.

Its not all doom and gloom for Microsoft though, XP is still their old faithful, by the time Windows 7 is launched, Vista will have matured and as Windows 7 will be 100% Vista compatible people will have far less fears about upgrading. They have the foundations laid with Vista already, being able to spend time on optimising, GUI etc should make for the OS Vista should of been.

Microsoft has learnt from its past mistakes about releasing information about planned features and is being far more tight lipped, which should help to minimise the negative publicity that occurred during the development and release of Vista. Windows 7 the story so far and Windows 7 - Wikipedia both have more details about Windows 7.