what is the recommended version for ITS?

HI Experts,

what is the recommended versions for ITS?

We have SAP R/3 4.6c and WAS 6.40 ................what will be the recommened versions ITS for the above said SAP R/3 4.6c and WAS 6.40 combination...........

and also furnish the list of all versions of SAP R/3 ,WAS and ITS........

Higher points will be rewarded for useful inputs........

Thanks in Advance,

Shakthi