I don't know why everybody's recommending virtual machines: there's a learning curve, and the OP mentioned he has problems in Windows.
Sucks that Win10 gets installed automatically. I'd look for solutions for that instead of side-stepping the problem. I would only start Linux if: the whole concept of Linux enthuses you, or you like learning geeky computer stuff, or you reeeeally like saving money.
I have to warn you that, as is with most popular open-source projects, the capabilities of Linux distributions is often exagerated (f.i. "you can run any Windows app via WINE").
If you have the Win7 installation medium, and a "normal" platter hard-disk (i.e. not an SSD), there's no risk to just install a Linux Distro. (Assuming all important data is backed up.) The easier distributions come with an installer similar to Windows', and install a graphic environment from the start.