Sometimes it can be yes. Though not allways.
The trick to sucessfull overclocking is:
A. Having the right hardware - using cheap components is guaranteed to cauze problems
C. The right software tools
Use a wide range of programs such as sandra, prime95, memtest86, games etc to thouroughly test your system out.
Increase the overclock in small steps, testing as you go.
Make notes of what works and what doesnt.
In your case more ram voltage may make the ram work better (i wouldnt go above 2.8v though)
More cpu voltage may make higher overclocks possible and stable, but increase thermal output.
A good cpu cooler is essential, as is good case coolign to disperse the heat.
Does anyone have any good links to tutorials? Also what are my chances of getting a 2.4Gb P4 (Northwood C) with some Corsair TwinX DDR500 up to 3GHz? Would I have to think about using Water/Compressor cooling or would I get away with a good Heatsink and Fan combined with say a Thermaltake Xaser III case (It has good cooling straight out of the box)?
Also I always wondered with all this extra voltage does it mean their is more running through the HD and Video Card? If so will it mean I'm gonna need HD coolers and custom video card fans? man... their is sooooooo much i need to know