Well security is always a concern. The IRC has a long history of people fucking with the unsuspecting. I imagine it's always a possibility with other types of chat, it''s just that the IRC is so old, that people have been playing with it forever. Every twellve year old hacker wannabe in the WORLD knows how to find software to cause mischief on the IRC... its like a rite of passage.
A java or flash enviornment is no guarntee of security. Otherwise the newer chat clients are lots easier to use, offer native support for file transfer, voice chat, webcams, etc.
If you haven't tried Skype yet you definitely should. It''s like a free telephone, with lots of awesome bells and whistles.
Skype official website – free download and free calls and internet calls
Really... check it out!