Dear Salah-ad-din,
You can get your family off windoze. First, what I will recommend you to is to get a RAM upgrade. Otherwise with 128 MB, you will not be able to get the power you need from SuSE nor MEPIS. Try to upgrade at least 512. CPU speed do not matter much. I was comfortably running SuSE 9.3 on an P3 500 with 384 MB of RAM.
Edit: You can try DSL (Damn Small Linux) on your machine. Follow this thread:
http://www.linuxquestions.org/questi...d.php?t=400680
You can run bookworm (if this is the Java game) on Linux [I tried a couple of mins ago]. With a Java platform you will not have a problem.
Lastly, Linux is full of choices: if you want Opera but not Mozilla, then go with it. But support Firefox ;-)
Regards.