Intel classifies their new Core chips into three groups- i3, i5 or i7. The i5 falls into the mid-range of these VERY fast new chips, while the i7 are the fastest ones of all. I'll skip the i3 since your question relates directly to the i5 vs. the i7.
All core i3 and i5 processors are dual-core, while all i7 processors except one (2.66GHz i7-620M) are quad-core chips. I believe that the two you're asking about are the-
2.26GHz Core i5-430M (which is had dual processing cores)and
1.6GHz Core i7-720QM (with four processing cores)
The i7-720QM is up to 26% faster than the i5-430M in some tests, which is a substantial performance difference. Or at least it sounds like a huge difference until you put it into perspective by comparing with the fastest Core 2 Duo- the 3.06GHz Core 2 Duo T9900. The 2.26GHz i5-430M is about 3% faster than the 3.06GHz T9900, just to illustrate how powerful even the i5 chips are!
The i5-430M is a great processor and will handle your HD videos with no problem! The quad-core processors are literally much more powerful than most users will ever be able to use! The quad-core chips also tend to run a bit hotter than the dual-core i7 and i5, so the laptop may be excessively hot in areas and/or the cooling fan(s) may run frequently or even run constantly!
I say go for the i5-430M and enjoy, it will still be the fastest notebook you've ever owned! If i were choosing between the two, it's what I would choose!
Hope this helps...take care!
I'm looking at 2 different Toshiba Satelites
The first has a Core7 1.6 GHz chip
The other has a Corei5 2.26GHz chip
Both have 4GB DDR3 RAM
Can someone explain what the difference in performance will be between the two?
No gaming but I expect to view HD video.