You need to research the warranties for your country. Some name brands don't offer much of a warranty if you live in India or some other locations. A reputable dealer doesn't hurt either. I would never buy a used or refurbished laptop. Order direct from Dell or hp if possible and have it built, even if it takes a couple of weeks to get it. Dell should have some deals in January at the end of it's quarter. This month was the end of the current quarter. I also like some of the Lenovo models.
For what it's worth Taimour, I just bought a Toshiba Portage R750 at BestBuy here in the US and I like it. It's pretty quick, small and light. Good for travel if that's what you're looking for. It weighs just 3.2 pounds. It has a 13.3 inch screen. Good sharp screen. It has an Intel i3 CPU and 4 gigs of RAM (I think, I'll have to check). Comes loaded with Windows 7 Home Premium 64 bit.