Originally Posted by Goodman
2-The laptop had Dos?
Then it would be a pretty old laptop & you may not have enough ram or HDD space to install Windows XP , win98se maybe?
If, subhendu has gotten a recent model Dell 15r, I don't think he will have trouble running any recent OS on it.
Dell 15r specs:
A laptop without a OS can be had from some companies(new, used, refurbed, etc.) or purchased second hand, or by other means(gift, given - because thought dead, etc.).
Just 'cause it has DOS on it, doesn't necessarily mean old.