In above posts I see you people a totally confused in the benefits for Nokia in using windows.
So, two paths.
I. Nokia immediately makes Lumia on Android.
1. It is a more developed ecosystem, and due to Nokia's bardname, and actual quality of their Lumia phones, Lumias would be bought by people. Arguably more so than if they were based on Windows.
2. Nokia would be all alone, GOOG would not provide any special treatment for Nokia, as there would be no benefit for GOOG in doing so.
3. Market share within the Android ecosystem would be rather small, although it would probably be growing, but it'd be pure hardware and marketing race with Samsung.
4. Should NOK fail, and go bankrupt there wouldn't be a company as interested as MSFT to buy it's phone division, and the shareholders would be doomed.
II. Nokia starts with Windows, and joins Android later.
1. Windows is an undeveloped but rapidly growing ecosystem, which Nokia easily dominates. This way Nokia benefits hugely from growth of the ecosystem. Within years, when Windows phone becomes one of THE ecosystems(with at least 33% share), Nokia still holds at least half of that.
2. Nokia is assisted by MSFT, both directly (Microsoft was directly paying 250 000 000$ per quarter to Nokia), and indirectly by marketing efforts. They did pay for advertisements. It is overall important, and especially important if you're short of $.
3. Well I touched this in #1. Nokia dominates Windows Phone, which is a rapidly growing ecosystem.
4. As an almost exclusive Windows Phone maker, Nokia is of interest for MSFT to acquire. It is an insurance from bankruptcy.
The sales of Nokia Asha & other phone lines deteriorated extremely quickly, way faster than one(me for example, and well.. All analyst I've read) would be expecting. So I do believe it is likely that Nokia did find itself with a lot less cash than it would like.
The deal is not yet finalized. And taking in to consideration it is a HUGE, & FREE advertisement for brand-names of both companies, I would not be surprised if the deal gets canceled(after a good hike in the phones sales in Q3 2013).