I wouldn't expect prices to fall though, more likely to keep going up although that applies to 775 stuff as well.
The pound is in freefall at the moment.
http://www.exchange-rates.org/history/USD/GBP/G/30
As of today it is $1.6015 to the pound. On the 27th September it was $1.87. That is a drop of 14% in less than a month and 6.5% since Monday alone.
It wasn't that long ago it was just over $2 to the pound.
In reality a 14% fall equates to a 17% increase in cost over here. eg a $500 item would have cost £267.37 on the 27th September and today would cost £312.20.
In reality all these echange rate changes have not feed through yet on the current stock (ocuk will have agreed the price of current stock before this weeks fall of 6.5%). If the Asus is back in at £20 today, the next stock they get will be another £20 more assuming the rate doesn't fall further which is unlikely.
Rates are expected to plummet even further.
That means currently, 775 stuff which is in stock has not actually gone up whereas the i7 stuff is all going be far more expensive. Therefore even the i7 cpus are going to be much more money than the current q9xxx chips.
I would imagine then that a like for like kit with same quantity of memory is more than likely to be way in excess of £300 difference.
For something which only gives you gains in applications and not games, £300 is a lot of money to spend elsewhere in the rig such as a 2nd graphics card, a bigger monitor, more memory, faster processor or even having two monitors.
The sweet point for buying a new system price wise was about 2-3 weeks ago although this week is still good as you can beat any exchange price increases on current stock. I would expect ALL computer items to be 10% more expensive in less than two weeks as stock gets bought and replaced.
Throw in ocuk 666 deal with 6% off and you are looking at 16% more next week or so. A lot of money if spending £2500 (£400).