I am listing out a few good laptops under Rs. 40K-
This one should be the best option for a laptop under the sub 40K price band. It runs on Intel Core i5 (4th Gen) clocking at 1.7 GHz with Turbo Boost Upto 2.7 GHz. It features a 15.6 inch HD LED wide screen display at 1366x768 resolution. Storage space is whopping 1 TB and it has 4 GB DDR3 RAM. It also DVD writer support. It does not come with Windows pre-installed- but you can install it separately. Price
The laptop is available on Flipkart at Rs. 39499. You can also buy it on EMI.
Dell Vostro 14 V3446
It runs on the same Intel 4th Gen Core i5 processor as in the case of above model. It sports a 14 inch HD wide screen display at 1366x768 resolution. Storage space is a bit less at 500 GB, but it has the same 4 GB DDR3 RAM. The best part with this device is it comes with Windows 8.1 pre-installed. It also has support for DVD writer. A good option for frequent travellers as it is light weight. Price
It is available at a price slightly higher than your limit of 40K at Rs. 41900 on Flipkart. You have EMI options on this device as well.
Toshiba Satellite C50-A X0012
Powered by Intel Core i5 (4th Gen) with clock speed of 1.6 GHz (Turbo Boost Upto 2.6 GHz), this one features 15.6 inch HD LED backlit display at 1366x768 resolution. Storage space is 500 GB and it has 4 GB DDR3 RAM. It has no OS pre-installed. It does support DVD writer. It is observed to perform better, but is a bit bulky.Price
Available on Flipkart at Rs. 35250, this is among the cheapest ones.
Online or Retail?
As far as your question on where to buy the laptops, I would suggest you to go for online purchase. Laptops and computers have high distributor/dealer margins and as such you will save a lot of money if you buy them from online stores. I would rate Flipkart as the best e-tailer in this segment.
Difference between 4th Gen and 5th Gen
The biggest difference between 4th and 5th gen intel processors is
- Better thermal compound is used in 5th Gen
- Extra power management circuit
- 5th gen processors are smaller in size
- Improved graphic performance
- Battery life improvements
I don't think it would make much of a difference for a normal user.