New systems

Hi all, I am the Network Administartor for a large 1500 user network, and next september I will be taking over two new IT suites. These have yet to be filled, and I would like to do it as cheaply as possible, whilst keeping security and stability high. How feasible do you think it is, and am I creating to much work by switching from NT4.0 to SuSE 7.0? Robb Bloomfield