You could try running the game under a different account. That could help if you have it set up to disable non-essential services, etc.
Actually, I'm sure I've seen a program mentioned somewhere to shut down non-essential stuff before gaming, and optionally restart it afterwards. However, a quick search only found an old topic;
How to close programs and services before gaming?There are several ways to setup a dual boot system. The easiest and safest, if you are at least comfortable with hardware changes, would be to turn the computer off and unplug the power cable from your main hard drive, then install Windows on a different drive. If you only have one drive, some motherboards may be able to boot off external backup drives, or you can install Windows to a USB key (Google for instructions).
Do you know any computer geeks that could give you a hand? Chances are anyone who has set up a dual boot system would probably have a spare hard drive lying around, from a previous upgrade.
There is no guarantee this will even help, so I'd hate to encourage you to try something potentially dangerous if you are not comfortable with installing/re-installing Windows, etc. A full backup should allow recovery from any problems, but it would still be a pain.