Thank you very much; that was helpful. I managed to assemble a lookup-table using David. I.e. a table with two columns:
Affy-ID (from) Entrez-ID (to)
10165372 57282
....
Now, what would be the fastest way to proceed? You mentioned a "small script"; which scripting language / environment would you consider appropriate. I was thinking of merging all data into Igor Pro and rearrange the data using Igors Scripting language. Seems a bit awkward, though. Do you know of a smoother way to achieve the import into cytoscape?