scripting language newbie - compatibility

[Kurt Aistinger]

Hello everybody!
I recently decided to learn a scripting language like perl, tcl or python
and can't decide which I should choose.
Someone told me that perl is source-compatible, you can take the source from
unix, copy it to windows and it runs, which is reallly cool I think.
Nevertheless, I think that programs in python are easier to read and to
understand and that they're shorter, which makes it more sympathic to me.
are python-programs source-compatible, too?

                    regards,
                                    Harald