#1.

Go for a P5Q motherboard if possible. The P5Q series are pretty OC-friendly, but I think they're incompatible with Nvidia cards. How much more (or less?) do you have to pay to switch the 9500GT for a Radeon HD 4850 or 4870?

Also, in practice, a 420W power supply will most likely not provide your components with as much as 420W of power. Your choice will most likely be sufficient, but upgrading to a 500W one still seems feasible. Corsair is a pretty good PSU brand.

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