Re:
You can try Jabber on Linux. As I know it has a lot of interfaces to various IM systems.
If you need run some other Win32 applications on Linux, there are two ways. First. you can install VMWare. VMWare is not emulating one of some operating systems, it is emulate hardware, therefore in VMWare you can install almost any OS which works on Intel.
Second, install Wine or WineX or Win4Lin. These products emulate Windows environment.