If you go with the common scene you would definitely want to go with the latest version of java(i.e 1.5).
Primarily because you get newer features, more predefined class and java 1.5 is faster the 1.4 .
And speed dose matter in an real time application.
So if you do not have something really BIG going for java 1.4 use 1.5
Do you really mean real time application? Or more real world applications? Because java is out of the box not really suited for real time applications.
If you meant real world application you could think of:
Generics
Enhanced for-loop
Auto(un)boxing
Varargs
Static imports
and much more
"Any fool can write code that a computer can understand. Good programmers write code that humans can understand." --- Martin Fowler
Please correct my English.
While I don't see where Anjali Pal didn't use professional language, or why the replay would be "junk", it should be pointed out that Java 5 has been declared obsolete by Sun, and should *not* be used for new projects; Java 6 is the way to go.