I tried running Doom 3 (was still in the early stages but don't think that this matters) and the noise wasn't as bad but then I played WoW again and the noise was at the same level as when playing Doom3. I've only tried this once though.
My temperature at idle is around 51C (used to be < 50C when I first built it) with 2k-3k RPM and spiked up to 68-75C with 4.5K+ RPM when I play WoW.
I did read that anything below 80C is fairly safe for a P4 but it's mainly the noise that's bugging me. Any help would be much appreciated.
Also, I opened the casing once when the noise started (after shutting off the PC) and it was quite warm inside the casing; my graphics card was probably the warmest one of all.
Below is my PC config (what I remember off my head at least ^^) :
P4 3.0GHz with HT and 2mb L2 Cache
2x512mb DDR400 Kingston RAM
128mb ATI x300SE
120GB SATA HDD
120GB IDE HDD
DVD-RW and CD-RW
PS - I was running WoW at default setting and I do believe that I should be able to run it at "high" settings with my current config. Doom3 was also run at default settings. I also have a casing fan.