<p>I am going to install SVN for my personal projects. Is it better to install it on a spare machine(Win XP) or will I save myself grief if I install it on the machine I use for development(Vista). </p>

Installing your repository on a separate machine is probably a better idea, since at a minimum, it will allow your source code to survive a hard drive crash on your development machine.
If you're new to SVN, you can't beat the free e-book from Red-Bean and O'Reilly ... Check out "Version Control with Subversion" here:
http://svnbook.red-bean.com/
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