Maxing out the VDD (chipset voltage) should be safe, so you might as well do it right from the beginning.
The CPU-temp basically relies on four factors:
cooling
voltage
frequency
degree of load
There are certain BIOS-settings to be aware of. Disable the following:
thermal throttling
system BIOS cachable
Video RAM cachable
FSB spread spectrum
AGP spread spectrum
Your cooler isn't that great, I think. Pay attention to the temperature - it shouldn't exceed 50 C during load. Personally I'd try to raise the vCore to the 1.75 - 1.80 range. Relax your memory timings for now, you can try to tighten them later. Also make sure the memory runs in sync with FSB, which you now should be ready to raise gradually.
You're gonna need to stability test your computer. You may have heard of Prime95, a renowned OC-program that stresses your system to the max in order to check wether or not it is stable. There are called torture tests. This program also has a benchmark which is great for stability testing. If your rig doesn't crash during this benchmark, you should be safe to increase the speed further (unless your temps go wild).
Prime95 is also useful in the sense that it raises the CPU-temp alot, especially one of the tests (it's described in the program). Let this test run for some time, as you monitor the temperature. You see, it's good to know how high the temp will get before settling down and gaming for hours (while temps are possibly getting too high). If the CPU-temp stays reasonably low during say 30 minutes of Primetesting, and the ambient temperature is fairly stable, you should be on the safe side no matter what application you run. Please note that Prime is designed to run for hours straight, but you'll find out pretty quickly when the system is beginning to get unstable, therefore I recommend you use the benchmark first (takes 30 secs or so).
Finally there are tons of details I haven't gone into, but as long as you don't melt your CPU or something, no harm is done. OCing takes a lot of experimenting, and you shouldn't try to find more than one component's limit at a time.
Anyway I hope this will help you getting started. When you have new dilemmas or questions you can always ask the guys at the forum.