I haven't really seen this issue before, however..
I did that multiple times. It only made it worse by making me have to download more programs, haha.
The software that usually comes packaged in the installer, you don't have to install that if you just untick the selection box that says to install it.
And the only help I've found on this topic mentions that it also depends on the provider you're getting the xchat installer from.
I use the xchat client from
http://www.silverex.org/news/
I'm pretty sure it came ready to go.
Otherwise, I wish you luck with your IRC client!