What is the risk of purchasing a used Netbook?

I need a netbook - 11inch screen- only for web browsing, reading articles, and some videos.

New Asus EEEBook is available for 14K on flipkart - Celeron Dual core+ 2gb ram.
Micromax, Iball, RDP with intel atom are available for 11K.

Used Asus EEBook and 2 year old Dell Netbooks are available in shops for only 6K. With 1 month working warranty.

1. What could go wrong with this purchase, except poor battery backup?

2. Somene mentioned - that over a usage of 2 years parts become slow because of heat. So this used netbook could be freezing within 1hr of use.

3. I heard Linux runs good on old/low end hardware.

Thanks in advance.