i have windows 7 installed using bootcamp from mavericks. Mavericks bootcamp only supports up to Windows 7. Am I able to do my free update from Windows 7 to Windows 10? Will it still work on my mac????
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First of all the golden rule is backing up before changing anything!

If you try any new thing please do not forget to make a bootable external clone of your OSX.
My experience follows for what it might be useful... or not at all (????)
In my MacBook 4.1 early 2008 for reasons I don't know, installing Windows 7 did not work at all neither with a DVD nor with an .iso, but...Windows 8.1 did work (???)

with the necessary drivers downloaded through BootCamp from Apple. Don't ask me why since I haven't the slightest idea, but it was so.
I have not yet done it but see no reason why Windows 10 should not replace my present Windows 8.1 as an upgrade on the Windows side.
However, according to Apple, a MacBook 4.1 is not among the macs able to run any newer Windows than Windows 7!!!!??

Therefore that info from Apple could be possibly questioned.
Again, if you try anything, be VERY cautious.

If it makes a mess of your OSX, have a bootable external clone drive to be able to restore your OSX from it.
I take no responsibility for any problem which might appear in your computer because of what happened in my old MacBook (of course!), but simply tell here my own experience even if i do not understand it.

Ed