You should also make note that when you download large files using mIRC, you are making yourself more likely to receive a virus or trojan horse. Now with that being said, If you want to use mIRC to chat, then here at these forums people can help you with any other questions you may have about mIRC. It is a great chat client and I think many would agree, its sad to see more people everyday are using it to download files with it than to use it to chat.
Anyways, I hope you understand my position on the subject. I cannot speak for everyone but I'm sure there are many who would agree.