My specs: Phenom II N930 (same as yours) and Radeon 4570M
With MTVU hack, the CPU is sufficient for this game, although the FPS drops to 50 FPS sometimes due to CPU bottlenecking.
Your GPU is weak, however. According to my test, my 4570M achieves 118 FPS on PCSX2 BIOS native res, while the Radeon 4200M only reaches 48 FPS (~40%). Your 4250M is only "slightly" faster than the 4200M.
I can only play FFXII at native resolution. 2x native res works in some parts but drops the FPS to 40 FPS on large areas. Even if you use native res, slow down is inevitable.
The bad news is you CANNOT upgrade a laptop integrated GPU (the Radeon 4250M). There is nothing to do 'till you can afford a new one.
Edit: Since your GPU is half speed mine, it should not have dropped to 20 FPS. 40+ FPS at native res is possible. In AMD Vision Control Center, set the CPU clock speed to constant
2000 Mhz - 2000 Mhz, not the default
800 Mhz - 2000 Mhz. I notice that the Phenom II N930 always underclocks itself to 1400 - 1700 Mhz when running PCSX2 and other games if you leave it on default settings.