Is it good to submit the same articles to different article directories?
It depends, but generally no. Google has clamped down on spam-marketing like this... but it's important to note the "spam" part of that. Consider these two situations:
a) If you write a genuinely useful and interesting article that you then push out to a variety of sites (with a link to your own site in your byline, for example), the content itself will likely get a down-rate for being duplicate (unless it's syndicated, which is a different thing), but not for being spam. Overall, you'll benefit because the people who read the article will be likely to visit you.
b) If you write a thinly-veiled bit of marketing crap (fake review, etc.) that includes a link (or more than one) to your site in the text, then push it out to as many article directories as you can, you'll likely get down-rates for both duplicate content and the fact that your writing is spam. And your readers won't visit, because it's spammy marketing crap.
Or should I spin the article first before submitting?
No, no, no, no, no and no. Never, ever, ever spin anything, ever. Spinning does NOT create useful content and has no other purpose in modern Internet marketing than making you look VERY stupid.
The days of spamming links to your site in the hopes of getting higher PR are gone. Generating lots of crappy links like those provided from spun (i.e. useless and illegible) content get your site down-rated by Google - and by the other engines once they catch up. Bad practice. Do not spin.
Will submitting the same article to different directories affect my Page Ranking?
Yes. Any linking activity affects PR, since PR is simply a calculation based on the number of incoming links to your site. The fact that PR is pretty much irrelevant since it's only a teeny, tiny part of your site ranking is, however, more important... especially when you consider that the tiny boost in PR generated by your spammy links is overwhelmingly negated by the fact that they're spammy links!