Diferences between 4850 dual and single slot

what are the differences between the 4850 single slot and the 4850 dual slot?

is it that the single slot uses only 1 pci slot while the dual uses 2 but that the single slot makes more noise and heat??

i had in mind the sapphire 4850 512mb

im going to buy in spain, and the store im purshasing doesnt have de his version
they have the single and the dual slot versions

the dual slot being cheaper

maybe i should get the single slot and an aditional cooler like these ones:

- http://www.tranza.com/softis/pv/1301/ANTEC-VCOOL-VGA/

- http://www.pccomponentes.com/ARCTI [...] REV_2.html

im not from spain ..a friend of mine is there nowadays and hes bringing me one

the one u say is the single slot... i can get that for 130 €

but i can also get the dual slot version for 115 €

( http://www.newegg.com/Product/Prod [...] 6814102824 )

i dont know the difference (apart from using 1 or 2 slots)

Dual slot pro:
-Dual slot provides better cooling
-Dual slot usually expells hot air out of the case (much like I do when I start ranting)

Cons:
- Render a second slot useless

Otherwise there really isn't a difference. Noise is more a function of cooler and fan quality than single or dual slot.. though usually better cooling performance of a dual slot also means it will be quieter. If you don't need the slot, and have room, there is no reason not to get a dual slot card.