If you intend using the CALL material on several computers in your centre, enquire about the technical specifications of the programme, and your legal right to make several copies. Some CD ROMs cannot be set up in a network configuration, others can. It's all technical, but you need to know beforehand. But many CALL programmes these days come from the UK or the USA, and may need to be shipped in. COST At some stage of the process, you will want to know the cost of the product, either on a unit basis, or for several authorised copies or for networking.
Prices are often on a sliding scale, so they are worth a second look.
You will notice that cost is not necessarily listed as the first criteria. Value for money is vital in language software. Some very reasonably priced programmes are extremely elaborate and very well designed, while some very expensive and sophisticated CD ROMs run out of interest after an hour or so. There must be an attraction or interest maintained when using the material, so check that the general presentation is modern, colourful, enticing, instructive, clear, logical and basically sensible. This follows on from the previous point and implies that the programme is user-friendly.