  The Grid technologies are in ongoing development. Using current Grid toolkits
like the Globus toolkit gives one the possibility to build up virtual
organizations. Although these tookits are in still under development and do not
feature all functionality, they can already now be used to set up an efficient
computing environment for physics collaborations with only moderate work. We
discuss in this paper the use of such a computing structure in two running
experiments - the AMANDA (AMANDA = Antarctic muon and neutrino detector array)
neutrino telescope and the D0 experiment at Tevatron, Fermilab. One of the main
features of our approach is to avoid reprogramming of the existing software
which is based on several programming languages (FORTRAN, C/C++, JAVA). This
was realized with software layers around the collaboration software taking care
about in- and output, user notification, tracking of running jobs, etc. A
further important aspect is the resolution of library dependencies, which occur
when a user runs self-compiled jobs on machines, where these libraries are not
installed. These dependencies are also resolved with this layers.
