Amen to substance over style.
That's still the best machine all-rounder around that price if its still on sale at the price however. The Dell machines are weaker for gaming, the Advent is slightly faster in the GPU department, however has a weaker CPU and is hard to get hold of now (although is much cheaper and recommended if you can find one!). The Clevo 860 is again I7, configurable memory, GTX280m, about 1.2-1.3 for one of those (sold by several brands, I'd recommend Kobalt but there's a backlog which is to be considered as you sound like you want the laptop *soon*).
The ball is in your court here, the UK laptop market is unfortunately not really that well equipped unlike the US one, and offers much more limited selection for non-work related use, especially around the £1k mark.
Anything at this price with a GTX260/280m or an ATI 4830/50 are going to be the amongst the best gaming laptops you can buy right now at this price range. (They're in a similar performance region to the desktop 9800GTX/GT, roughly performing in this order 4830m<GTX260m<4850m<GTX280m)
New ATI cards are due in a couple of months, but you want to buy now, making this irrelevant. Buildwise both Clevo and HP are decent brands if you're not buying rock bottom budget, which you're not, the Advent is reasonable as an MSI, but not quite a good.
The HP is more stylish, the Advent 7555 has a better GPU (its an MSI GT725 under the repackaged skin). The Clevo has I7 as well, but will take much longer to arrive, costs more and performance difference over the advent is not huge (~5%).
Most other laptops in this price region in the UK use a weaker GPU, and wont be of interest to you.
Sorry if my advice has come off the wrong way, I've not based this all around style, just tried to incorporate what you might think is important, and trying to look at a wider picture. As I have no idea what she uses to game right now I've got no performance guage to try and judge how she would find a machine based around these GPUs anyway.