Pretty much any recent series can support dual monitor.
The question is what you're using it for.
For basic test, no concern for quality a ATi Radeon 9200SE or nVidia GeForce 4MX would be more than adequate (with the 9200 having slightly better 2D quality with faster RAMDACs).
For some a little more 'capable' then the the Radeon 9550 or GFFX5500+ (avoid the FX5200 as most have the same RAMDACs as the GF4MX).
For something more serious for quality IQ, then the GF6200/7300 or Radeon X1300, with the X1300 having very slightly better video playback, and also have dual-link DVI support for if you do move to a large LCD in the future.
Now really it's all about what you're doing with it there's a whole world of possibilities, and any card with a DVI-I connector (which is just about all of them nowadays, carried both the digital and analogue signal and thus even if the second connector is DVI you're fine for analogue.