It depends on your definition of normal. You will be running two systems simultaneously, the Linux inside xp so everything will be slower although an average user may not notice much. I've never heard of 'Whonix' os can't tell you anything about it. You might be better off starting with a more widely used distribution. You can go to the distrowatch site and get a general idea of what the more common Linux distributions are. Check the Page Hit Ranking list on the right side of the page below:
You mention Knoppix in your thread title so I'm not sure what you are planning to use. Knoppix can be installed to a hard drive but was not designed for that and its developers specifically state on their site that it is best not to unless you consider yourself a 'Linux Expert'.