A very practical network problem for the effective deployment of a transatlantic computational GRID which is the current under-utilisation of the newly available fat long pipes drives the following work towards the investigation of whether new TCP stacks can solve such issue. The paper proves the necessary use of IP-QOS and investigates the conditions under which IP-QOS and new/standard TCP stacks can coexist such that high utilisation as well as good stability and inter-class protection is achieved.