As far as I know, KSP does not handle Multi-core right now. Also, KSP is a 32-Bit (Please correct me if I'm wrong) software and does not use more ram than your 32bit system will allow. No big deal there. But 9800GT is an old-badass (use to get 2 of them in SLI) Graphic card. I guess what you wanna change is the GPU (a better graphics card) and the RAM(CAS9 for good speed), and go to a "64bit-ish" OS to get the maximum benefit of your RAM. Also, in future, look up for a better CPU (and of course the MotherBoard that go with it) because your CPU will become the bottleneck of your computer performance. However don't go for a i7 multi-core, for the obvious reason stated earlier. A simple fast i3 "k-ish" (for O/C purpose and still dual core for when KSP will be upgraded) should REALLY do the trick.