These instructions are for installing windows 10 preview, on a separate newly made partition. This will allow you to keep your existing windows 8.1, all files, programs, and everything else. They are left untouched. And the Windows 10 preview will essentially be on its own. This also allows for dual boot, in which upon booting up, you will have 30 seconds to pick whether or not you want windows 8.1 or windows 10. The pros are that the preview will run 100% off your hardware. No virtual machine, no problems. It also allows you to keep everything you have right now, and have 100% access to it at anytime. This way when the preview ends, or you don't like the preview, or you experience bugs, you can just boot back into your windows 8.1. The only cons I'm aware of, are that #1, you loose the amount of hard drive space in which you allow for windows 10 to use. #2, any/all programs you have on windows 8.1 will have to be redownloaded/installed into/onto windows 10. They will still remain 100% in your windows 8.1, but you wont have access to them when your in windows 10. Normally not a problem, unless its programs that allow only a specified number of installs. Like office, iTunes, kindle, ect. I've searched high and low, and finally was able to do this myself. So this is for those who don't want to spend hours figuring this out. So, step 1. Download the windows 10 iso. This will take a while. Download it, but don't install it. http://windows.microsoft.com/en-us/windows/preview Step 2. Download all surface pro 3 drivers. Save these somewhere easily findable on your surface pro 3, or on a usb flash drive. You will need these upon first boot after installing windows 10, especially since without these you will not have wifi access. http://www.microsoft.com/en-us/download/details.aspx?id=38826 Step 3. Download EaseUS Partition Master. The free version will work just fine. This will allow you to shrink your c:/ to make a separate partition in which to install windows 10. Normally I use disk management through windows, but since the surface saves files throughout the entire drive, I wasn't allowed to shrink my c:/ more than 200-300mb. Depending how you plan to use windows 10 and what you plan to install on it, I would allow 20-50gb for the windows 10 partition. I used 50gb. http://download.cnet.com/EaseUS-Partition-Master-Free-Edition/3000-2248_4-10863346.html After shrinking/repartitioning you drive, downloading the windows preview iso, and downloading surface pro 3 drivers. Your ready for the process. Step 4. Normally you would use windows 7 downloader/installer to make a bootable usb. But the format that this program formats your usb drive, isn't usable for windows 8 or windows 10. So follow the steps in this link, and it will work. http://www.manjeetjakhar.com/2013/09/how-to-create-windows-81-installation.html Step 5. After using diskpart and following those directions, I just mounted the iso (which opens it up and instead of being a single iso file, its now like 3 folders and several files). Once you mount and can see several files/folders, just click/drag/move those onto your usb that you made through step 4. Step 5. Time to shut down your surface pro and access bios. After its shut down, hold the volume up button while holding the power button. Hold the volume up button until the surface logo shows up. Once your in bios, make sure that secure boot is disabled/turned off, and make sure that usb boots before your ssd. Once this is done, save your settings, and restart. Step 6. Restart, with the usb in. Follow instructions and install windows. Click custom install, and then choose the location that windows 10 installs. When your looking at the list of several partitions, just find the one labeled and size of the partition you made for your windows 10. Step 7. After the whole installation is done, you will be in either desktop or start menu. You wont have most drivers loaded or needed and cant even access your internet. So you need to go to the control panel, go into device manager. And under each of the hundred or so items, right click and hit update driver. Then select the location of the driver, then find the location you saved the drivers you downloaded, and click ok. Select just the broad folder of all drivers, not specific, this will help. Some items wont be updated, but a lot will. Not sure which ones were all needed to be updated but its about 30 or so. Which is why I just say do them all, that way you don't miss any. Also, several updated drivers will want to reboot. Don't o this every time, just wait until all your drivers are updated and then reboot. Step 8. Upon rebooting from installing/updating drivers, hold the volume up bottom to get back into bios. Once back into bios, turn back on secure boot. Save and exit. Step 9. Now that your back into windows 10, have drivers installed and updated. You should be good to go. Make sure you look for windows updated. And then do your own personal tweaks to settings, apps, programs, ect. I had so many problems until I used these exact steps, after using these, Ihad a working windows 10 dual boot install. Any problems/comments/questions, please post below. Hope this helps those, I know I wished there was this post before I started, and saved myself hours of my time.