sigma ef 580 dg any good?

greetings from south africa:p
this is my first post,im very new so please bear with me...

i have a canon 400d(xti) and im wanting to use the flash(sigma ef 580) for off camera shooting. im very new to this and dont have a large budget, sooo...
can it be done?

Did you mean the Sigma 530 DG? And if so did you want opinions of the 530 DG ST or the DG Super? As far as I know Sigma does not have a 580 flash.

I have two Sigma 500 DG Supers and I'm very happy with them. I would be really happy with 530EX II's, but that's a different thread.

If you're going to do off camera shooting you should look into the Vivtar 285HV or the Sunpack 383. Both are much less expensive than the Sigma.

Yes, you obviously mean the 530s as the there are not 580s existing in their production list, nor are the 500s for sale anymore (unless you are buying an old product). And since you mentioned off-camera shooting, I assume that you are talking about the super version.
I have two 530 supers at the moment and I have to warn you that it's not user friendly at all. Modelling flash in conjunction with wireless flash leads to freezes (you need to disconnect the batteries to get it working again).
Also, there is no EV override for the master or slave. Adjusting the EV setting makes no difference for the exposure, something I am extremely annoyed about.