Since I have used these forums many times and found them very helpful, I hope I can help someone in turn.
x64 (and probably x86) Windows 10 runs fine on the 2010 13" MacBook Pro (well, as well as it can with a Core 2 Duo and 6GB of RAM). However, it is a little involved.
What you need prepared (on a flash drive perhaps):
1) Boot Camp 5.1.5769
2) NVidia 327.23 Drivers
3) Three files from the Apple support package for Windows 7 (you can download the package through boot camp assistant, or from somewhere on Apple's web site): AppleKeyboardInstaller64.exe, AppleMultiTouchTrackPadInstaller64.exe, and the NVidia directory (with NVidiaChipset and Win7 folders inside).
4) If you want the LCD to display colors correctly, take the color profile from OS X.
1) Install Windows 10. You can trick boot camp assistant with a Windows 7 disc if you like to get the support package, or you can just do the partitioning yourself.
2) Do NOT connect to the internet, because Windows Update will force install a driver for the 320M that is broken (thanks, Microsoft).
3) Find bootcamp.msi, and run msiexec /i bootcamp.msi in an elevated cmd. Also run the trackpad and keyboard installer.
4) Watch Apple's drivers get installed.
5) Go to device manager, find the 2 problem devices, point the 'update driver' mechanism to the NVidia directory and watch your drivers get installed.
6) Install the NVidia 327.23 drivers and fix the color profile if you like.
7) This is the critical step: download the update blocker utility from Microsoft here: https://support.microsoft.com/en-us/kb/3073930. Connect to the internet and (quickly) run the utility and block the NVidia drivers from installing. Once they get onto your system, they will reinstall themselves over any other driver, which is what happened to me. If this happens to you, run DDU (display driver uninstaller) to get rid of the 2015 driver once and for all, reinstall the right driver, and block the update again. These drivers DO NOT WORK and will result in corrupt graphics, even in XP/7/whatever. You can tell if you have them by looking in device manager and looking at the driver date for the 320M. The right drivers are from 2013, and the bad drivers are from 2015.
8) We're not done yet. Apple's HFS drivers break some Windows 10 features (at the time of this writing) so go to windows/system32/drivers and rename AppleHFS.sys and AppleMNT.sys to something else (AppleHFS_disabled.sys for example). You can access the HFS partition with some other utility, such as Paragon's free HFS extension, but I haven't tried it. For example, I couldn't access storage and apps & features in the settings panel with them enabled, it would crash.
9) Your text will be blurry in some applications because Windows tries to auto scale them because who knows. Set custom scaling to 100% in settings.
10) Disable ethernet because it causes huge DPC spikes. Re-enable when you're using it. Also disable the IR and bluetooth radios because they're useless. Also turn off auto brightness because it's equally pointless.
11) Reboot and you're done. I also disabled Microsoft's data collection through the registry: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\DataCollection\AllowTel emetry and change to 0, disabled start menu web search with a group policy and settings setting, and disabled the Windows Update service because I am not OK with MS installing whatever they like on my computer given their track record. I also did a few other tweaks like disabling cortana and removing live tiles from the start menu, but that's up to you. I also disabled automatic driver updating (which didn't do anything because WU does what it likes), removed the "Windows 10 Education Edition" watermark with the Universal Watermark Disabler, and disabled "occasionally show suggestions in start menu," all of which are speed tweaks which help running 10 on a C2D.
12) If you happen to use Norton, and have exhausted your licenses due to reinstalling Windows, the client has a bug that will hang on activation in 10. Pick a preferred web browser in settings, run activation and you'll be good.
13) Change the background from a boring Windows window.
Everything works, including trackpad, backlight, iSight, whatever. Windows 10 runs as well as it would on any other 5 year old computer. I can't afford a new computer and I need Windows for some school work. 10 is free and the start screen is the dumbest idea since the 9x core.