I'm a layperson. I need a computer that will not freeze up when I'm trying to do multiple things -- e.g. 20 chrome tabs, some pdf's, multiple word documents, possibly using STATA also. I am trying to decide between a new-ish ideapad with an i5-6200 and a used thinkpad with an i7 3520. Does an i5 being a more recent generation makes it better than an older i7? I am willing to buy and install extra RAM for either if necessary. I don't store a lot of stuff on my computer, so hard drive size isn't a huge deal for me.
Assuming comparable price, should I go for the 2015 new ideapad or the 2011-2012 used thinkpad?
A properly configured system (which includes hardware, OS, drivers, and applications) should not "freeze". But, to your question, you are considering processors which are three generations and three years apart:
http://ark.intel.com/compare/64893,88193 ARK | Compare Intel® Products
You will find graphics support on the older processor something to be concerned about.
In my opinion, go for the later processor and memory. And, while disk size may not be important to you, disk speed should be. I would consider a SSD in this case since size is not much of a concern. And, I would probably consider other manufacturers in addition to Lenovo.
Just my opinion.
Good information from Al.
Besides checking on ark.intel.com you may want to try the link below: