In what way exactly is Scan a bad site? I've been buying components from then for quite some time, and I've never had any problems. You might be thinking of Ebuyer, with their notoriously bad shipping problem!
If you want, have a look at the fact that CCL Online still charges a 165 pounds for an OEM version of the X2 3800, compared to about 110 to almost all other e-tailers.
No my friend, stick to Scan, Overclockers.co.uk, and even Ebuyer and Komplett if you must.
Anyway, back on topic, might I suggest this, in the same pricerange.
Gainward 512MB 7900GT Golden Sample
I'm thinking it will perform better than the X1800.