guys ....pllzzzz dont shove your old hardware to some one who is asking for a new card recommendation...buy talking b/w and beating the competition etc etc.....3.5k for a 6600GT makes me laugh i just sold my 8600GT 256 MB for 3750 with 2+ years of warranty remaining ....the price is justifiable cause a new one costs 5k 
so a 6600gt shud not cost more than 2k (MAX)
Try to get a ati graphics card(that is in case you have a PC labelled as a heritage PC)...you might have a better chance with ati than Nvidia
Links for some agp cards by Sapphire
HD 3850
2600 XT
2600 Pro
I recommend neither of the above...just sell your old junk and get a new PC (considering you are having a 10k budget)

so a 6600gt shud not cost more than 2k (MAX)
Try to get a ati graphics card(that is in case you have a PC labelled as a heritage PC)...you might have a better chance with ati than Nvidia
Links for some agp cards by Sapphire
HD 3850
2600 XT
2600 Pro
I recommend neither of the above...just sell your old junk and get a new PC (considering you are having a 10k budget)