JAVA_HOME = c:\j2sdk1.4.1_02 [I have jsdk1.4]
path = %PATH%;%JAVA_HOME%\\bin
CLASSPATH = .;%JAVA_HOME%\bin;

Next reboot your system.

Create a classpath environment variable, store all your class files in this.

with this u will b able to excute java  from any of the drives.

If this doesnt solve the purpose, put all the java files in a package with
classpath set, this wud solve the problem