What is the minimum for editing XDCam IMX material?

Is it possible to edit it on a iMac ALU 2GHZ COre2duo with 4GB memory and FCP Studio 2?

Yes, its fast enough for both SD and HD. But the 20" model (alu) iMac does have a lower quality screen (16 bits). This can be a problem. The 24" iMac has a high quality screen (24 bits).

There's only room for one internal drive, so extra drives must be external ones. Buy external firewire drives with two firewire ports so you can daisychain them (I have six in one chain). Stay away from external USB drives, they are to slow.

Two GB memory will be enough, you will get a small advantage if you take four GB.

You must be aware that there's no room for cards like Kona, Decklink and alike.

Yes Arvid

That would be more than suffiicient, but you will need an external media drive too. With the new iMac you have a FW800 port, so I would recommend adding a FW800 raid drive, such as thse provided by G-Technology, CalDigit or Lacie.

Also, if you can budget for it, consider adding a second monitor and/or Matrox MXO (to drive a reference output)

Hope it helps
Andy

Do you have any advice what kind of display that would be good together with iMac 20"?

the 23" Apple Cinema Display is still a darn fine monitor, coupled with a Matrox MXO its becomes a color critical reference monitor for HD/SD.

the Dell Ultrasharp 24" Widescreen is widely regarded as being a very good deal, cheaper than the ACD yet with better specs in some regards, and for a video guy the multiple inputs can serve a host of monitoring functions