By the time 955 @ 3.8 - 4ghz will start to struggle with games u'll be able to pick 8-12 core CPU for 70quid.
Don't try to future-proof, it's not worth it ; ).
And even 15-25% difference isnt that big in real world performance, once the PII will start to struggle, the i5 will do as well or 2-3months after that. It's not like 50-100% difference where PII will pull off 30FPS and i5 will do 60FPS, by the time PII gets to 30fps, the i5 won't do much better either, and the difference you've saved could most likely get you new, faster CPU by that time.
But yeh, i5 is decently priced so it's not a bad option either but on the other hand I wouldn't spend more than you need to. It's best to upgrade CPU every 1-2yrs nowadays.
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Either way, i5 or PII will be much better choice than i3 so whatever you choose will be fine.
Don't try to future-proof, it's not worth it ; ).
And even 15-25% difference isnt that big in real world performance, once the PII will start to struggle, the i5 will do as well or 2-3months after that. It's not like 50-100% difference where PII will pull off 30FPS and i5 will do 60FPS, by the time PII gets to 30fps, the i5 won't do much better either, and the difference you've saved could most likely get you new, faster CPU by that time.
But yeh, i5 is decently priced so it's not a bad option either but on the other hand I wouldn't spend more than you need to. It's best to upgrade CPU every 1-2yrs nowadays.
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Either way, i5 or PII will be much better choice than i3 so whatever you choose will be fine.