shanmuk surya

Hi to all,
my doubt is whether the java virtual machine is available in the operating system or as part of the jdk kit.
It is said that the jvm is system dependent and the .class files are system independent.
for ex:I have two pcs ,where linux runs on one machine and windows on another machine.I have a jdk1.5 kit to install on both of the systems.so does the same jdk1.5 kit works for both the operating systems or i should get some other jdk.