if u wanna play medium Graphics games like underground & with low-medium settings den u can cut down some bucks on 7600GT & can go for some of d earliers basic cards... u would save around 8K.
for 5k, you should eye a 6600GT.
For 15k, you get a 7900GS, 17k for 7900GT, look out for a 7900GTO as well, 7900GTX is out of budget and looses to a 1900XT within the same price range.
OR juz wait for 2-3 months for some new Graphics cards supporting directx10.
After 3-4 months for 15k you will get a 7950GT and if you are extremely lucky a 1900XT for a tad more, or you might get a 1800XT around 15k then.
& even buying normal keyboard & mouse would not be more den 450-500 bucks.