Help! My computer is killing my patience (and my project)

Hi Guys, it's been a while since i posted. Please see my sig. line for my system info.
 
I can't get this PC to stop with the buffer drops and I've gotten to the point where I've kicked out many plug-ins, and reduced the quality of my project just to try to unload some of the processes the program is doing. I've turned off Internet Explorer, and AVG, I've gone through the cpu processes with a fine tooth comb to see if memory or processes else where are running and killing my speed. Tried adjustments to the buffer during recording and playback to economize there to. Nothing is stopping the drop outs and crackles. 
 
I've gone so far as to check every wave form I've recorded up close, and the drop outs aren't shown in the wave profile, so it's not actually on the recording. The buffer just drops when ever it wants to on playback. (or tracking) So my fear is, when i go to mix this project down it's going to be filled with pops and crackles.
 
To try to make things better:
I've since added an additional internal hard drive dedicated to just this 13 song project and it's Cakewalk project files. After 2 years of messing around with this thing, i had the idea of replacing the CPU, but since it's a 3 year old mobo with a FCLGA1156 socket, there is no hope for finding anything better than the core i have.
 
I have no synths, no midi, no drum machines, it's all mic'd instruments and vocals, lined in bass (the worst offending track for drop outs) and this is relatively a very basic 13 song rock project (13 individual CWB files) Some songs have up to 15-20 tracks, most only 12-15 tracks.
(I even dumped all my vst plugins that didn't come with Sonar 8, and replaced them with Sonitas FX stuff to see if that was the issue, but... nope)
 
So what i am asking is two things, first can i get a better i5 or i7 quad core to swap out my i3 duo? Will it even make a difference?
Or have i got my routing wrong and I've set up my busses incorrectly, and taxing the system with my own stupidity?
 
At this point, I would even be willing to even drop box send a CWB file of one of my projects, to one of the moderators to look at, to see what I've done wrong. I've been told that my system should easily handle this project.
 
I know some of you must still be using sonar 8. 
Help out a guy who's band has waited to long for it's CD :)
Thanks,
Rob.
 
 

Full system spec please, along with interface details, driver mode etc.
 
Without this information it's a bit of a crapshoot