Just got back from ASDA Trafford Park, purchased an XBox 360 Arcade plus a Wireless Contoller, + Forza 3 for £105.
I'd previously had an xbox but got the dreaded (expected?) RROD. Appreciate that this model doesn't come with a HDD but as I've already got one, can simply pop it in the new box.
I've checked the manfucaturing date and it's listed as 2009-10-09, which to my knowledge should be the more hardy Jasper chipset (hopefully less likely to get the RROD).
Ultimately though, it's brand new and will come with the full warranty!
They appear to have been shipped in pretty recently all packaged up along with Forza 3. They're upstairs by the tills near George.
Not sure if a nationwide deal, but for those who've already got the HHD (like me) and are on a serious budget, it seems quite a good deal for a decent console.