As far as i know the 4850 comes only in GDDR3 and a Powercolor GDDR4 version
I think it is a typo get the 4850 but see that you have a stable enough PSU to support it and also the price is very low is that a second hand card or you are not in India?
im suprised too gettin it so cheap<by d way my psu is 400w & a cheap one from Mercury>
my vender says it is so bcuz it is a ddr2 ram one.i live in chandigarh and surely its a first hand one.
Please see the above link: Sapphire has no DDR2 HD4850
I think he is qouting the HD 4350/4550 series: They are the only HD 4xxx to come out with DDR2 :
Obviously it is good to check out the card by going to the dealers shop itself and if it is a GDDR3 HD4850 then go for it before the dealer can note it as a mistake!
And i think that card is not to be fitted with that PSU mate: It is cheap and not meant to run even a Geforce 8600GT much less a HD4850
If it is the HD4350/4550 as i think it is then go for the HD4670 GDDR3 : It is good enough for 1024*768 gaming but with that too see that the PSU is changed to a proper one please!