1. Sure, 9600 PROs are good cards. Powercolor isn't the best manufacturer, but I still have a Powercolor 9500-modded-to-PRO in one of my secondary computers that's served me amazingly well.
2. Yes, but not necessary. You will see results much better than stock by simply by removing the thermal tape that sits between the stock cooler and GPU, and replacing it with thermal grease (Arctic silver is great).
Once you've reached the limits of this method and you want higher clockspeeds, aftermarket coolers are next to try.
3. Some of Powercolors "PRO" cards are "PRO ez"... which means reduced memory clockspeeds. But if yours came with 400 core/300 memory stock speeds it's a true 9600 PRO.
4. The only difference is, once again, clockspeeds. The 9600XT is running at 500 core/300 memory. Most 9600 PROs can reach this speed with sufficient cooling, in alot of cases with stock cooling. But like I said, at the very least, replace the thermal tape with real thermal paste.
5.If you want to try stock, go for it. But if you see artifacts (white dots or texture tearing) in games, pull back the clockspeeds. It's running too hot, or it can't handle the overclock.
And pay attention to Plekto's notes about good case cooling. It's good advice... a video card can only get as cool as your case allows it to.
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<b>Radeon <font color=red>9700 PRO</b></font color=red> <i>(o/c 332/345)</i>
<b>AthlonXP <font color=red>3200+</b></font color=red> <i>(Barton 2500+ o/c 400 FSB)</i>
<b>3dMark03: <font color=red>5,354</b>