Id pick up a nice new Gigabyte GA-P55A-UD3 with usb 3.0/Sata 6.0 for just over 100 quid and a oem Core i5 750 for £140, looking at the benchies on anandtech even in winrar/hd converting and gaming the Core i5 750 handles similar and better in some gaming benchies then the Core i7-920.
Unless you really are going all out with dual graphic cards and want 8-12gig and crazy overclocks, I dont think its worth the extra £££.
Its sometimes nice to have an smaller/more efficent cooler and cheaper chip, doesnt look too me that triple channel and HT are making much difference especially if u look at winrar scores here:
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3634&p=15
And gaming scores here:
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3634&p=16
See Core i5 750 pulling ahead faster then Core i7-920 at almost £60-80 cheaper....
Give it another year or 2 and both sockets will proberly be replaced anyhow... So you could take your pick literally.