You didn't take the time to read the stickies in the Tekkit bug board OP? http://forums.technicpack.net/index.php/topic,2834.0.html
Just install Java 7 and it will work
I am going to buy a computer, and I wonder if AMD A6-3500 and 4 GB RAM is enough to host a server for 5-10 players? I am not going to play on the computer myself, it is only going to be a server.