I purchased Lenovo G580 20157 in late 2012 for around 26000 rupees. Today in January 2016 I have windows 10 installed on this device and everything works fine. During upgrade to windows 10 I messed up with boot thing but the service guy helped in getting my laptop recovered without any data loss.
4 GB Ram is more than needed but the downside is the processor. Sound quality is amazing, its loud than any high range laptop.
For 26k it was definitely a buy for me