Seems like a CPU bottleneck. The games you listed are likely single-threaded, so that doesn't help.
2500K, as your friend has
5400 Score, 6 cores
5400/6=900 per core
6300 Score, 4 cores
6300/4=1575 per core
The 2500K is effectively 75% faster than the CPU you have, assuming no overclocks.
Your laptop CPU is better than your Desktop CPU.
7700 Score, 4 cores
7700/4=1925 per core
The 3630QM is effectively 115% faster than your Desktop CPU, assuming no overclocks.
The fact that graphical settings have little to no effect on your FPS "Crashes" in combat really prove it is a CPU issue. If you want to see for yourself, open the windows task manager when you test your framerate. Let it run in the background, then when you get a FPS drop, tab out and look at the performance tab. If one of the charts on the monitor is maxxed out, that means a core is reaching its maximum and if that'a happening at 15FPS, that is a clear bottleneck.
I understand this may not be news you want to hear, I know what is is like to have to replace your CPU, but I had a worse experience than you. I had an Athlon 64 X2 for a long time and I got up to 100FPS in WoW, but when I did a 25 man Raid, I dropped down to 1 FPS. I knew nothing of computers back then, but eventually I figured it out with help from others.
If you can overclock your CPU enough to let it not bottleneck your GPU, you should be fine. Since you're not dropping to 1 FPS, there is still some hope that you can get by with it for a while.Edited by Shadow11377 - 7/22/13 at 1:10pm