Due to the upcoming holiday I'm pondering purchases and such. Now, I haven't actually played any previous Elder Scrolls but I've been reading up on Elder Scrolls IV: Oblivion and have seen the outstanding reviews. Would anyone care to advise me on whether it would be a good idea to buy Oblivion this Christmas or whether I should give it a miss because I haven't played the others.

Since there is really no underlying storyline, you're not missing out on anything; the Elder Scrolls games are connected by a common mythology and world, but are set in different 'states' of that world.

Keep in mind that Oblivion is a western-style RPG; the focus is on character development and an open-ended gameplay, as opposed to a linear storyline like Final Fantasy (commonly known as console RPGs, or Japanese RPGs). I'd suggest renting it out before buying.