CPUz will tell you for sure what your processor is and what it supports. I know the early Athlons and some Athlon XPs didn't have SSE... My Desknote(XP 2000 processor) didn't support it so I couldn't run Premiere Pro...
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Desktop * Athlon X2 4200 | 2G RAM | 160G HD | 7600GT
Laptop1 * C2D T5550 | 3G RAM | 120G HD | Intel x3100
Laptop2 * C2D T5250 | 2G RAM | 160G HD | Intel x3100
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