Hey m8,
Sorry to hear you are still having problems. Are you running 64-bit or 32-bit version of windows and which flavor? How far does your load meter go?
In essence a Mac and a PC should technically both be suitable to do what you are trying to accomplish. Loads of people are doing it on either platform. The specs look good enough. I have ran Traktor on Windows XP on a 7 year old laptop. Granted, no room left for any other process, but Traktor ran without hickups.
Are you running 2 or 4 deck, key lock on or off? There is quite a few areas to look at.
We can dig some deeper into this through private message if you like.
Greetinx,
C.