Whats the difference please?

Am looking at buying a new computer and Hubby wants to know, firstly, whats the difference between DDR2 and DDR3 (RAM) and secondly, whats the difference between Intel i7 and Intel 2.0 Dual Core Processors?

Obviously we want to get the best so want to know what to go for.

Any help great appreciated,

Thanks Guys

Wendy

 

This will explain DDR2 and 3

http://www.neoseeker.com/Articles/Hardware/Reviews/ddr2_vs_ddr3/

And this for Intel

http://www.extremetech.com/article2/0,2845,2333764,00.asp

 

Thank you VERY much!! I appreciate it )