Samsung syncmaster 305t

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*30inch screen + MacPro -> low resolution only ???*
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The screen is this one: http://tiny.cc/305T
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(a)
I cannot get the MacPro running with the Samsung Display ALONE;
it always needs another (Cinema) Display on the MiniDisplayPort.
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But we do not have a spare CinemaDisplay for always,
the Samsung305T should be THE only display.
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Is there a way to persuade the MacPro to live with one display only
(plugged into the DVI-slot), or does there always need to be
something plugged into the "MiniDisplayPort" ???
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With that one Samsung screen alone,
directly after booting up there's the Apple logo on the Samsung,
but then it looses any picture, and starts blinking colours
(as if the resolution is wrong)
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Please tell me the tweak to persuade OS X to always use the screen
on the (wide) DVI-port, not the MiniDisplayPort. Thanks.
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(b)
I am not sure if the 2560x1600 resolution is Mac-compatible at all.
I can get it only up to 1280x800 pixels, not above.
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This page gives "compatible graphics cards" for that Screen:
http://tiny.cc/305T or:
http://www.samsung.com/ca/consumer/office/monitors/lcd/LS30HUBCB/XAA/index.idx?p agetype=prd_detail&tab=spec
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Compatible graphic card:
Nvidia Geforce 7900GT,
GeForce 7800,
GeForce 7600,
Quadro FX3000 (AGP Type)
ATI Radeon X1900XTX,
Radeon X1900XT,
Radeon X1800XT
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We have a MacPro with a NVIDIA GeForce GT 120
http://support.apple.com/kb/SP506
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So the Samsung screen might even not be compatible at all to Macs?
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(c)
Would perhaps this adapter solve it ???
http://store.apple.com/ie/product/MB571Z/A
"Mini DisplayPort to Dual-Link DVI Adapter"
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With that adapter, then there would be
something plugged into the MiniDisplayPort.
That should solve (a).
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But what about (b) the 2560x1600 resolution on the Samsung?
Will the MacPro THEN be able to create that resolution?
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That "Dual-Link DVI" adapter is quite expensive,
but if it is the only solution, apart from returning the screen ...
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Thanks a lot!