Replacing laptop cpu, worth it?

[Sixense]

So apparently I won't be able to afford a new gaming machine this year, got me thinking, will I get any noticeable improvements if I change my cpu?

Current laptop in signature, looking at i5-580M or i7-620/640M, as they're same 35W as my current 350M. Don't know if I can change the gpu chip in there, haven't seen any, except for 780M or something similar for Alienwares.

Any help much appreciated, planning to buy on weekend if it's worth it (like £25 for i5 and £40 for i7s)

Playing World of Tanks and War Thunder mainly, some Civ5.

 

[Sixense]

Lordzargon, it's a web browsing and small gaming, i.e. WoT, WT, Civ5, Terraria, some Source engine games.

P.B., what's an 'mxm gpu'?

 

[Sixense]

So I've ordered myself an i7-640M @ 2.8 GHz, we'll see how it improves my laptop (if it doesn't explode right away)

 

[Sixense]

Report back and let us know

It finally arrived yesterday, took 2 hr to replace it (basically because I forgot to add some TIM after cleaning everything off and remembered just before turning it on >.<)

Laptop seems a bit snappier, WoT and WT is way more stable, it doesn't stutter anymore when enemies get spotted, maybe even a few FPSes were added, or maybe it's just that it doesn't drop that often.

All in all, I'm pretty happy with it. News sites with a bunch of ads don't lag nearly at all, while with my i3 I could just barely browse them, and I can watch 1080p Youtube without freezes every 2 seconds and 720p doesn't lag at all.