On Nvidia hardware OpenGL and AA will work on both heads. Only Xv (hardware video scaling needed for DVDs / Divx) will work on only one head accelerated.
The card you want is something GF4 MX or GF4 TI based. Both cards support the same (twi)nview stuff. At the moment nvidia is more pushing Geforce4 Ti boards with twinview. Most of those boards ship with 1xVGA, 1xDVI and 1xtvout. (for a second VGA screen you need to use a convertor which is included)
The GF4 MX support this stuff too but it can be that it is hard to find to find an MX4 supporting 2x VGA. Most ship with 1xVGA +1xTVOUT. But I found some boards with the stuff you need. (for example cards from Gainward and MSI)