Budget Refurbished Thinkpads and Lenovos or possible better options?

[sr2002]

Hi, I am currently trying to purchase a laptop on a tight budget. I am planing to spend anything up to 550$US.
The only options I could find in that price range were in the Lenovo Outlet store.
I'm Looking at the Follwoing: (I will be putting a 250GB SSD instead of the stock HDD)

Thinkpad E531: 3632QM i7 + 4gb

Thinkpad E431: 3230M i5 + 4gb

Ideadpad U410/U310: 3337U i5 + 4gb + 710m Nvidia

Ideapad U410: 3537U i7 + 8gb + 710m Nvidia

Ideapad Z510: 4700MQ i7 + 8gb

Also of the above are essentially in the same price range (500-600$) except the U310 which for 370$ and the E431 i5 which is for 450$.

I am planing to use the notebook for college for running certain simulation programs for cricuit design and digital design. I will be doing some casual video edition nothing too serious and the usual web browsing.

My question is, are the above laptops good for my needs? Will buying an IVY bridge cpu make it obsolete faster? Are the thinkpads worth paying the same money for an older i7 ?
Also, I'm worried about the whole wifi problems with lenovo, does anyone have any expereince with refurbished Lenovo computers?

If there are better options, also please let me know.

 

[sr2002]

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