^^Uhh...no. Totally obsolete. For a cheap option, I recommend the ASUS Xonar DS. [The DX is more capable, but I wouldn't sink too much money into such an old PC]
Odds are, one of two things are causing your PC to slow down:
1: Bad soundcard drivers
2: Weak CPU
In any case, getting a soundcard will NOT help if its the 2nd, because sound isn't HW accelerated. So it won't help any. System specs would help a bit...