Standard -- Professional and Enterprise are the expensive versions and come with a few more cds full of other packages but if you want to get started and have everything you will need just use the standard installation cds.
so i will be getting in professional and enterprise versions are extra free softwares and books is it. but the price diff between professinal and enterprise seems to be hugh definetly there must be some added value, or iam wrong
Well along with the nice box and glossy manual, you are also esentially buying support contracts. Now, I don't know specifically about the various product offerings of redhat - but esentially, that is the model that someone like redhat adopts; they take an open source product but provide "enterprise level" support along with it so that silly corporate types will buy the product.
You don't need any of that. Just plain ol open source free beer standard distro is all you need.
For example, I remember seeing some product offering at redhat a few months ago for their database server whatever. It was just RH linux packaged up with postgresql in the pretty box but also along with the enterprise level support.