I live in the U.S., perhaps things are more expensive over in Belgium, I don't know. However, here you can build an 8800GT-512 SLI rig for around $650 without much effort mostly from newegg. Anyone who doesn't calculate price/performance on any purchase, except pure benchers with money bleeding out their ears who care about performance at any cost, is a fool and likely to run into financial trouble as they likely apply it to everything in their life, money be damned. By the way, it's "Tiger," not "Tigro."
EDIT:
Here's an example build I found and made in five minutes of work, if you wanted to meet my target of $650 you could just drop the CPU to a lower-end dual core and you'd be a scant amount over it with a CPU such as an Allendale for $60-70 oc'd to 3.0ghz or so... this is a quad-core rig with near-GX2 performance, 2GB ram, real motherboard/case/psu/etc., plenty of storage, etc. (hard drive could be shaven down too a few bucks such as a $30-40 200-250gb jobbie). It adds up to $662 with a dual-core CPU, $642 with a smaller hard drive and a dual-core CPU, or as shown $792. So, please try to tell me that for anyone but a hardcore bencher, again that $650 is not a lot for one computer's part?
Q6600 $200 when added to cart
http://shop2.frys.com/product/5101696
Motherboard with X-Fi sound onboard $140-30rebate=110
http://www.newegg.com/Product/Produc...82E16813130080
2gb 1-stick RAM module PC2-6400 $35
http://www.newegg.com/Product/Produc...82E16820609283
Rosewill case w/ free shipping ATX (non-junky) $39
http://www.newegg.com/Product/Produc...82E16811147088
Rosewill 550w SLI PSU well-rated on various real review sites $65 shipped
http://www.newegg.com/Product/Produc...82E16817182090
2x 8800GT 512 video cards in SLI mode, various, example $160-30rebate=130x2=$260
http://www.newegg.com/Product/Produc...82E16814121224
DVD burner, various Lite-On/etc. drives $23 w/ free shipping example
http://www.newegg.com/Product/Produc...82E16827106228
hard drive 500gb 7200.11 Seagate $60 shipped via various specials every week or two at various vendors