Mary, I know nothing about Mac's but have visited the sites for the software you mentioned.

Hearme does not support Mac's but intend to do so some time in the future.

IQC say: IQC PPC Runs on all Power PC Based Mac OS Machines. ICQ 68k Supports 68030-68040 cpu based machines

I am pretty sure you nead Real Player 7 for the Mudcat Radio and the mimimum spec is:

PowerPC 604 processor (200 MHz or faster)
Mac OS 8.1 or later
32 MB RAM and 65 MB virtual memory.
25 MB free space on your hard disk
14.4Kbps modem (audio only); 28.8Kpbs modem (video)
Internet connection and 4.0 browser (Internet Explorer or Netscape Navigator) Perhaps somebody will be able to advise you based on this information.

Jon