Guidance/suggestions for buying a laptop or laptop graphics card advice

I have a Dell L502XPS with a Geforce GT 540M GFX card, i5 processor and 6GB of DDR3 RAM. I’ve recently moved and there are a few little niggles that I have with what is otherwise an excellent system and want to replace it with something brand new (or manufacturer refurbished) and want a slight upgrade but really know nothing when it comes to graphics cards so I was hoping that someone can make a recommendation on a laptop with a better graphics card. Not fussed about hard drive size as I have a decent triple-platter 1TB Western Digital one which is very quick. With or without Windows 7/8 or OS-free - not fussed.

Can anyone suggest a good model, preferably from a more reliable company - or a good site to get a better lappy that I can order from within the UK? Or at the very least suggest a graphics card within a laptop to look for? I have done much Googling but am as confused as ever about the cards. I have around £600 I can spend, maybe £700.

Gfx cards are still not common for Laptops.

We could probably give you a better suggestion if we knew what do you do that requires an upgrade to the graphics performance. Are you playing games or what?

But I would rather spend that amount of money on a desktop,and keep that laptop for other use,after all,it’s still a good overall performer…

Thanks everyone, I got a Dell L521X with a Geforce GT 640M (2GB) from Dell Outlet for £600 ($979 US), good as new literally. Came with only 4GB of RAM so spent £50 ($81 US) on an extra 8GB. Now my only problem is getting 5.1 sound out of it, as unlike my old L502X there is no S/PDIF out and even though the HDMI and minidisplay port (got a triple monitor setup now) both output audio, it’s only 2 channel as that’s all that the onboard sound supports. External USB sound card time!