Thanks for your suggestions!
The cheapest Q9450 I could find at the moment was around 275€ plus shipping at mindfactory.de, where I'm going to get some other components to. I'll see that I can limit it to as few stores as possible to save shipping costs.
I'd like to get a PCIe2 board with and DDR2, so that I may switch to a new card some day without getting a new board...looks like it'll be the GA-X48-DQ6. Slightly more expensive but a newer chpset as well.
The modular cabling is accounted for, and the Nine Hundred should provide ample cooling for now.
I'm not sure if the extra cost for the Ultra is justified, I think I'll go with a GTX.
Including a 750GB HDD, some generic DVD Writer, a Creatve "X-Fi Music", some cables and shipping ( I managed to limit it to 3 stores) and substracting 60€ that someone still owes me that adds up to
1.473,98€, about what I intended to spend.
Thanks for your suggestions again