You can download VMware for free, it has some limitations on the free trial version, but you can try it before you buy it that way. You should know it's possible to run both Win7 & Win10 on the same hard drive, but it normally takes expert skill to do so. If you wish to try this I'll give you a couple of cautions here.
Making dual-boot or multi-boot OS configurations can be tricky and usually requires expert level computer skills. The very first thing to do is to make sure you
HAVE ALL YOUR PERSONAL DATA BACKED UP TO EXTERNAL MEDIA BEFORE PROCEEDING! from your W7 setup. It's also a good idea to use an Image backup program such as
Macrium Reflect to back up your existing W7 setup, as if you scramble your dual-boot setup, or you just tire of it and wish to go back to your original W7 configuration; you can do so in a couple of hours with Macrium, versus a week or two to completely reinstall your W7 from Recovery discs, reinstall all your apps, and restore/reintegrate all your data again. We call this a complete rebuild, and it's usually very time consuming and often frustrating, even to us experts.
**Note: Don't forget to make your Rescue Media with the Macrium as if you format your bootdrive, or change out your bootdrive with a different physical hardrive, you'll need this in order to put your computer back to it's original or pre-dual-boot condition! Next, is that you'll need to run the standard W10 download upgrade to key your W7 license key converted to a W10 key for the windows. Once this is done, you'll need to download the free MCT tool from the Microsoft website and create either a DVD disc from ISO file or a USB stick from ISO file that will contain the W10 OS that you can do a Clean Install from. The goal there is to create a W10 on top of a W7 installation, or to Clean Install the W10 and then install your W7 on top of the W10. There can be some issues with each, and so this may take you multiple attempts to get it working.
I've done dual-boots this way, as well as doing a W10-Linux Ubuntu dual boot which can also be done.
You may be wondering, why not just use LoboVerde's suggestion of running a VMware-type virtual environment for your W7 or W10? The most common answer there is that many legacy programs won't run in a VMware virtual environment, say programs from XP or W7, but they will run in a dual-boot or single-boot setup of W7. If you are doing software testing on multiple versions of windows for yourself or for a software company, you'll most likely have to have both setups; a dual-boot computer with W7 & W10, and a single OS boot such as W7, and run the W10 in a VMware-type virtual environment. If you've done software beta testing before, you'll understand this immediately, if not, this is why one needs to test in both types of configurations.
One last thing, it's very important to know that dual-boot OS configurations on a single bootdrive, are risky and are more prone to failure.
When I worked at IBM we used to configure 5-different OSes on the same laptop computer for each of our 70 field engineers who worked out of my office, as we never knew which Client they would be visiting that had which particular OS. In some days they might visit 3 or 4 different clients with 3 or 4 different OSes. We finally had to nix it, as we were constantly rebuilding the Engineer's laptops, and the cost outweighed the benefits of having multi-boot laptops versus dedicated laptops for dedicated OSes; for example: 1 laptop with Windows95, 1 laptop with OS2, 1 laptop with NetWare, 1 laptop for NT, etc. So, if you choose to do a dual-boot computer it's really smart to use a reliable Disk Image Backup software such as Macrium I mentioned above, and if you accidentally crash or scramble 1 or both OSes on the computer, it's very easy to go backwards to your original single-OS boot configuration, either W7 or W10, and can be done in only an hour or two instead of a very time consuming week or two as mentioned earlier.
Hope that helps.
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