Mike,
I have to agree with Dave's skepticism about what you can do with a blurry 320x240 image. I assume you are stuck with that size and can't improve it by rescanning at a higher resolution from some source print.
On that basis, I concur with Philip's recommendation of Focus Magic. It uses a unique deconvolution algorithm that can actually restore some focus. It can also upsize by a factor of two or four. Focus Magic comes in two parts: a standalone application and a Photoshop plug-in. I usually use both the plug-in and the standalone on an image because each has capabilities that the other lacks.
I am enthusiastic about my purchase of Focus Magic and it is one of my most-used tools. Focus Magic has a limited usage demo that will let you have some idea what it can do on your image. Click on this link for more information:
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http://www.focusmagic.com>
-- Burton --