what videocard should I take? need new videocard

so I wanna buy a new videocard because I can’t stream with the one I have now.
these are my computer stats:

processor: AMD Athlon™ 64 X2 Dual Core Processor 4200+ 2.21 GHz
RAM: 2.00GB
motherboard: ASUS M2N-MX SE

somebody got any idea?
I’m sorry but I don’t know a lot of computers and videocards.
thanks for the help