Well, it's best you ask again when you actually back in Feb
I'm guessing the res of your Dell is gonna be 2560, so I would say the GTX460 SLI would definitely lacking (in both grunt and VRAM).
The best graphic card set up you could get (launch at Jan 9) is gonna be pair of 7970 3GB in crossfire, but that's gonna set you back around £850~£900
Reviews for 7970 is already out, and it is (or gonna be) the fastest single GPU card. While it is a decent card, people feel that rather than the typical extra performance that come naturally with new gen card, AMD is charging a premium for their new gen cards (pushes their flagship card price from previous £300 ish up to £400 ish, and mid-range from £200 ish up to £300 ish); instead of pricing it as the same level as GTX580 to drive its price down, they STACK their pricing on top of the already LAST GEN premium priced GTX580, as well as their own last gen cards (6950 and 6970). Also, with the GPU moving from 40nm to 28nm, people were expecting huge performance boost...but the 7970 turns out only a small margin faster than the GTX580, which was on the old 40nm process! And for those extra % of speed, people have to pay the same or more % of money for it...so it's not better bang for bucks in anyway. Lots of people are underwhelmed by the performance on this 28nm graphic card and question if AMD is even taking advantage of the 28nm process properly, and would rather wait and see what Nvidia can bring to the table and 'get the 28nm process done right" (however, Nvidia next gen cards are rumoured not going to be out until Q2 of 2012). But to be fair, there are also people suggested that the current overclocks of the 7970 are all done on stock voltage and lack voltage tweak, so we won't be able to see what the 7970 is fully capable of until then.
But either way, by the time you return in Feb, there should
hopefully be reviews of performance of 7970 overclocked with voltage tweak, so you could then decide rather you would want to grab a pair of 7970 3GB on the spot, or be more patient and wait for Nvidia to launch their next gen cards and hopefully stop AMD from stacking the price of the cards on top of last gen cards, and then you could decide to go for AMD or Nvidia card.
If the price of a pair of 7970 3GB scare the living hell out of you, you should pray that the 7950 3GB would be cheaper by a fair margin (not much higher than £300 each), and performance not too much slower than the 7970. But it is unlikely, as the US price for the 7970 is $550 (£420), and the 7950 is at $100 cheaper on $450 (£287). Rip off Britian price is usually
at least 20% on top of after exchange, so the prices of 7950 and 7970 are expected to be at
at least £350/£420.
