We just moved to Europe, The Netherlands. Of course I took my CAPRESSO C1000 with me. I was wondering whether the internal transformer can be replaced with one that works with 220V, or whether it can

What does the label say on the base does it say
110-240v
i dont think it will
you can use a 250v to 110v if it came from the states
it will use 110v so you need a step down
ignore the differance from 220v to 240v its not that important 20v in the main
http://www.ebay.co.uk/sch/i.html?_kw=240+110+transformer

youll find one on ebay cheep
http://www.ebay.co.uk/sch/i.html?_nkw=220v%20to%20110v&ssPageName=GSTL

check the wattage the maker uses and get a transformer that can supply enough juce

i would take it too a local shop sells electronics like maplin mondo radioshake local similar
and they can guide you with free advice

Most unlikely it can be replaced. the whole design needs to be changed. a stepdown transformer has to be heavy rating to handle the machine, otherwise the transformer will burn out.