Hey guys,

I've got a band called Anti Icon (www.myspace.com/antiiconmetal) but we have some vocal problems.
We got a singing installation with enough wattage (i think) but our vocalist just can't get over the guitars and drums.

We thought it might be the cables.
Now a friend of mine told me a XLR-cable sounds louder and better, is this right?
thanks anyway!

Rien, Belgium
XLR cables will only work if your mic has an XLR input (by the wway you worded it you lead me to believe you are using 1/4 inch jacks)

and secondly, cables are not the problem most likely, its is likely the way you have wired up your system
The cable really isn't going to make any noticable difference. Try EQ'ing the vocals, with a boost at 3kHz, which will help them cut through, and cut those frequencies from other instruments.