The i5-450M and i5-520M both have a base clock speed of 2.4Ghz and Turbo Boost to 2.67Ghz on two cores, although on one core it's 2.67GHz vs 2.93GHz - since PCSX2 uses two cores, I wouldn't expect this to matter much. Apart from that, the i5-520M has three features that the i5-450M doesn't - VT-d, the new AES instructions, and Intel Trusted Execution technology. That last one is a security feature, while I doubt PCSX2 uses VT-d or AES-NI. As such, I doubt the i5-520M would be any better for PCSX2 than an i5-450M. As for i5-520M vs 2.66GHz Core 2 Duo, the i5-520M performs something like a 2.8-3GHz Core 2 Duo in most other tasks. If you want a big improvement, you need an i7-620M or overclocking.