Audio interface for live laptop performance?

For under $100 you really won’t get decent results. You need to consider the cost of the interface, as well as the reliability and drivers. I would say minimum $250—$300 for a decent Firewire or USB interface. The Apogee Duet is really nice and runs $500.

Do you think I’ll notice THAT much of a sonic difference? This is mostly for live playing in clubs through a Roland RD-500. won’t really be using it for recording. Thanks

It’s hard to say what you’d notice. Depends on the PA system, mostly. The point being, If you already have a crap soundcard, you’re not going to improve things with a different crap soundcard.