My complaint with MIRC, which I've used plenty is the following:
1. Unless it's a secured channel with a reputable host, mayhem in the form of nasty script kiddies(people who do programming tricks to mess with other chatters and their pc's) can abound. Tis often a main conduit of trojans and viruses that for those who are not net or pc savvy, can be burned pretty badly.
2. Commands: I have no problems with them, but again for those who are not familar or not pc savvy, they may prove to be arduous for many to use.
3. Maintenance: In order to protect the users of a site on MIRC, there's got to be someone with a LOT of knowledge concerning security, etiquette, set up and so on to be in the channel at all times, as well as setting up bots and so on. It's a very time consuming job. That person also has to be able to teach , without getting frustrated, and teach many. Site ops and mods have a pretty difficult job in this respect.
Some of us have been using msn messenger with no problems. It's easy to secure, lightweight and you don't have to close down programs or use commands to operate. You can get up to 25 people in one conversation if desired, and also speak one on one at the same time if needed. It also has voice capabilites, Cam capabilities(y'all oughta see 1-95 nekkid, just ain't purty


), also has file transfer protocol which filters through your anitvirus. Also, interactive games and such can be played, with ease.
The drawbacks are again the limit of participants in one conversation is 25, but for myself......it's confusing at 25!.Also what I've seen most forums who utilize msn is to make an msn list, to whioch you may add whom you wish. If someone adds you to whom which you have no desire to talk to......don't accept the invitation and if you find out later it's not your desire to communicate with this person anymore.....just block 'em and delete 'em. This way you have control over who can converse with you .
The requirements for IRC are programs such as MIRC, PIRCH, Acidmax
Some charge after so much usage.
The requirements for MSN messenger are either a download @ msn.com or Windows messenger, which is a slightly streamlined version of msn messenger......comes with XP home and XP pro automatically and interfaces with msn messenger. However, I personally recommend downloading the msn messenger that is 5 mb's...a little more bang for no bucks