Blaaaaaaaaaaaaaa this is very much

$2500 US?

wait for the hexacore i7's and a nice 30" monitor should take about $1000 off of your budget or a 28" LCD for $340.

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1) hexacore i7, 6 cores, 12 threads, comes out in Q1 2010

2) well 30" of 16:9 goodness with a 2560x1600 4MP screen, No TV in your price range is going to beat it but you'll need a couple of good graphics cards so two 4890's or the 58xx series if you build next year.

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If u want a screen go for Samsung 2343BW, it's 249€ and has DVI and VGA connectivity. It's excellent for watching movies and working with documents and 3D modeling since it has a 2048 x 1152 Pixel Resolution.
Other then that, at your budget you can choose whatever parts u want. I personally wouldn't mix i7 with an Nvidia graphics card since they have a performance hit together but other then that...

CPU: i7 920

Motherboard: X58-UD3R (budget),ASUS P6T (mid), X5-UD5 (high end, 3-SLI)
Note: X58-UD3R can do both SLI/CrossFire with a BIOS update.

RAM: Any good brand (OCZ, GSkill, Corsair,etc) DDR3 1333 3*2GB (6GB total)

Case: Antec 900, CM HAF 932, Antec 1200, or any other case you like that has enough space

HDD: 2*640GB in RAID for data
300GB WD Velociraptor for OS

GPU: ATI 4890

Total of that should be about $900-1200 USD or so. With your budget you could spend the rest on a very nice LCD (30" ($800+)or 22-24"($250+) if you don't have space/money).

You may also want to consider a nice water cooling system for the CPU and/or GPU if your interested in that.

edit:
Also get a x64 OS. You can ger the free Win 7 RC and upgrade the OS later this year. Also if you don't have an external back up system spend money on that too.

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^Water cooling is not required at all, but the option is there considering your budget. A good air cooler (like TRUE 120, S1283,V8) will be fine for you

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^Right. For good fans (in terms of CFM vs. noise) take a look at Yate Loon(best) or Scythe (good).

As for the GPU, it really depends on the resolution and the game. Some games run better on the X2 cards and/or some games don't change much in terms of performance. Take a look at some game benchmarks for CoD4,Crysis,FarCry,etc and see.

Imo, I would personally wait till July as the new i5 CPUs should be out.

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Looks good. Imo, unless you game quite a lot you could reduce costs with a single 4850/4870 OR 4770 in CrossFire which is better than a single 4890. Providing that the 4890 is only a little less performance than 4870X2 you are better off (more bang for buck) with the 4770.
See: http://www.tomshardware.com/reviews/radeon-geforce-grap...

wooah... what price range exaclty? 500usd or 2500usd?

and are you going to OC? and to what amount?

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case and PSU: antec 1200 + 1000W antec quattro $319.98
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

GPU: Sapphire HD 4770 512mb x 2 = $104.99 x2 = $209.98
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

CPU and cooler: intel i7 920 + Noctua nH-u12P $344.98
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

HDMI cable and thermal paste: gold plated hdmi-hdmi + AS5 thermal compund $13.98
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

HDD: WD Caviar Black 750gb $79.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

RAM + motherboard: ddr3 3 x2gb OCZ platinum 1600mhz cl7 + asus p6t X58= $322.98
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

LCD: 24" LG FULL HDMI 1920x1080 p $299.99 (u can get bigger & less quality for cheaper if u want)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

TOTAL (excluding post/rebates): $1591.88 USD


NB: you could cut down on PSU and monitor, and u could up the GPU and mobo if u wanted

^Realize that the OP said he lives in Europe so Newegg prices and their prices are not even close. The European prices are almost always .7-1.5x higher. I realized this after checking some of the European specific stores.

@OP: Are you talking about CrossFire 4870 or the dual GPU 4870(aka 4870X2). I am thinking you are talking about the dual GPU 4870. Also input lag won't be too much of an issue unless you are playing pro imo. Even with a 6-7ms response rate I can usually place in the top 4 for COD4 and Halo CE. Resolution detail (higher = better sniping etc) plays a much better role in your performance in a game assuming there won't be network/GPU lag. Also a good mouse plays a very important role in fps. I use a G5 (2nd one btw, first G5's middle button(scroll) started to lag from abuse lol)

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True that.

As for the GPU mind linking me to it?

if ur gonna OC it, then u probably will want to get one like a said... unless its only 3.3ghz or less... otherwise ur temps will go WAY up...

with that case + the CPU cooler, ur sure to get good temps

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^Yup, looks good. I was worried cause I didn't know if the brand you chose was reputable. Build looks good! Go for it!

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^Just grab some dust filters. Imo, it's not a good idea to put a PC inside a fully enclosed cabinet.

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^Yes, the 1200 comes with filters

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Have you thought about a air filter for the room? Worked for me in my basement. Just have to get good quality one and it should work very well.

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Yes, I was talking about the machine. It will not damage the PC in any way (unless you physically put it INSIDE the PC case). If you just leave it in a corner a few feet away from the PC you'll be fine. I have been using one for about 2 years now and it works well.

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^Yes. Btw, the basement room that I work in (have PCs in) is only about 225 sq feet. And I use this one: http://www.consumersearch.com/air-purifiers/honeywell-e...

Managed to get it for $110 during a sale.

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OCing:
http://www.bit-tech.net/hardware/cpus/2008/11/06/overcl...

Best one I found that's specific to your board:
http://images.tweaktown.com/imagebank/Core%20i7%20920%2...(ENG).pdf
lol, it's by Gigabyte itself!

Only change I would make: Use Prime95 Small FFT insted of the program they used. Also stress test for 6+hrs. And OC in the BIOS only. DO NOT use EasyTune to OC. Also if you installed DES (Dynamic Energy Saver) software provided with the board un install it.

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^The pumps don't provide enough air, as in the air flow is quite slow for a pump. Here is the US I can get a 3 pack for ~$10 and each can can last for 2-3 full cleanings of an Antec 900.

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^ Good luck then.  

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HSF: XIGMATEK S1283 with i7 bolt in kit.