well 9600gt I think will support DX 10.1 whereas DX 10.
But well, I hear that 9800GT is going to come out and hopefully I'll be seeing these in the specs:
Memory Type: GDDR4
Memory Size: 512MB
And hopefully GDDR4 is for real just like GDDR3 was against GDDR2. People tell me that GDDR4 is barely better than GDDR3 and I hope that is not the case. Also when Nvidia implements Aegis's physX technology into their cards that would be awesome.
I wouldn't buy a separate PhysX card but to use it whenever necessary for free however little, that's cool!