@amiga1260:
If you stay away from 3.5" harddrives, the stock A1200 PSU will get you quite far. It is atleast enough to power my A1200 with a Blizzard1260, a stick of 128MB ram, the stock 170MB 2.5" harddrive, a CNet-CN40BC PCMCIA-network card and a little 50x50mm fan.
/Patrik
