Well, I have heard this so many times now that I have decided to give up my GTS 250. Along with the PSU, it is now installed in my cousin's system - he needs it right now as he has 45 days free before he begins his job. He is happy to have it and I am happy to get rid of it
The biggest reason why I bought GTS 250 instead of HD 4870/4850 was that I just couldn't find the ATI cards. Their vendor network in India is really poor, it seems! Plus, I don't think I needed a 4870 because my display has a resolution of only 1440X900, for which a GTS 250 should be sufficient.
In the next month or so, I will set out to upgrade my whole system, including the cabinet, PSU, motherboard, processor, RAM and of course, the graphics card. Perhaps a 4890 will become affordable to me by then. My question may considered to be answered.
Thanks to those huys who took the time to help me out. Your suggestions will be needed again when I upgrade my PC